Timeline

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Silhouettes of the Aishi Bloodline (excluding Ayato).

This article documents the timeline — a chronological account of events and historical milestones of the Yandere Simulator universe, including key developments in the Aishi bloodline and the evolution of Saikou Corp.

Overview

The timelines within the Yandere Simulator universe are each assigned specific names and designations.

• Timeline 0 — Base World. Represents the real world.
• Timeline 1 — The first divergence from Timeline 0, introducing the earliest differences. At the moment, it's unknown what exactly happens in this timeline, because it's a spoiler.
• Timeline 2 — Marks the point at which the divergence results in the existence of Saikou Corp, where its founder Saisho Saikou invented the transistor and a bunch of other technology, and has two daughters.
• Timeline 3 — Serves as the primary setting for the events of Yandere Simulator, with all gameplay-related timelines branching from this point. Saisho only has one daughter. 1980s Mode and 202X Mode take place.
  • Timeline 3-2X or Timeline 3-89-C-2X — The moment before gameplay begins. This is the point at which the timeline can branch further.
  • The 1980s Happy Ending is set in a sub-branch known as Timeline 3-H or 3-89-F. Ui Tunesu never snitches on Ryoba Aishi. Ryoba eliminates 9 rivals and confesses to Jokichi Yudasei.
  • 1980s Mission Mode is set in a sub-branch known as Timeline 3-89-M. Sumire kills Jokichi, and Ryoba starts working for the Yakuza.
  • 202X Mission Mode is set in a sub-branch known as Timeline 3-2X-M. Ayano murders Taro and begins working as an assassin for Info-chan.
  • The timeline you're in if you play through the game as a pacifist is set in a sub-branch known as Timeline 3-2X-P.
  • The Genocide Ending is set in a sub-branch known as Timeline 3-2X-G.
  • Custom Mode occurs across multiple branches such as Timeline 3C0, 3C1, 3C2, and so on.

The specific timeline documented in this article is referred to as "Timeline 3-89-C-2X-C."

Timeline 2

Main article: Fun Girl#Background

At some point in Timeline 2, Saisho Saikou — founder of the Saikou Corporation — had three children: twin daughters, Fun Girl and Ichiko, and a son, Ichirou. According to Fun Girl, Saisho was a ruthless individual, willing to go to any length to achieve his goals. He was reportedly preparing for an undisclosed, catastrophic event.

Upon discovering his plans, Fun Girl intended to expose him. In response, Saisho allegedly developed a device capable of nullifying the rules of time and space, erasing anything placed inside. During a public demonstration, he convinced Fun Girl to enter the machine. Unaware of its true purpose, she complied, assuming safety in front of an audience. The machine activated and erased her from existence, along with itself. According to Fun Girl, no one, not even Saisho, understood what occurred.

Timeline 3 – Current Timeline

Timeline 3 is nearly identical to Timeline 2, with a noticeable divergence: Saisho never invented the time-space nullification device. As a result, Fun Girl was never erased — but paradoxically, she does not exist in this timeline either, due to the device's absence.

Despite this, her twin sister Ichiko is inexplicably aware of her. Driven by an unknown bond, Ichiko has abandoned her responsibilities within the Saikou Family to search for her lost sibling. Fun Girl, aware of this effort, claims to have tried multiple times to stop her, believing the search to be futile.

Before the Events of the Aishi Condition

Main articles: Aishi Family, The Aishi Precursor

The Aishi Precursor, the earliest known ancestor of the Aishi Family, as depicted in Origin Dream.

• 500 — Bankotsuko's first appearance.
• 1779 — The Aishi Precursor is born.
• 1787 — Ms. Basu and an unnamed incubus have a daughter, Sakyu.
• 1788 — Ms. Basu and an unnamed vampire have a daughter, Inkyu.
• 1795 — The Aishi Precursor meets her "Senpai," with whom she fell in love.
• 1797 — An unknown third party informs the precursor's Senpai about her feelings for him. They formed a relationship and emigrated from their country to Japan together. Her Senpai was later held hostage by a paranormal being.

Events of the Aishi Condition

The Aishi Precursor locks the defeated enemy together with her senpai.

• 1797 — The Aishi Precursor saves her Senpai and defeats the paranormal "enemy" with a weapon named Heartrender, which puts the entity in a state similar to suspended animation for almost two and a half centuries. She is buried under the Confession Tree Hill, entangled in the tree's roots.After that, the Aishi Precursor and her Senpai married each other and started to use the "Aishi" surname. Aishi precursor starts to experience the Aishi condition, characterized by perpetual sense of emptiness until meeting an individual who triggers the "Senpai efffect", making it possible for one affected by Aishi Condition to feel emotions in aforementioned individual's presence.
• Early-1800s — A pair of elite monster slayers from the west arrived in Japan through supernatural means, and became almost single-handedly responsible for wiping out the entire monster population.
• 1800 — The First Aishi is born. She was abandoned as a baby and adopted by Jiro and Oume, an infertile couple who yearned to start a family. and was the first to exprience the Aishi Condition from her birth.
• 1818 — The First Aishi finds her Senpai. Anahiki Aishi is born. The condition, first observed in the 1st Aishi, began appearing in her descendants, suggesting a hereditary nature.
• 1819 — Katana Aishi is born.
• 1820 — Hasami Aishi is born.
• 1836 — Anahiki finds her Senpai. Sameba Aishi is born.
  • Shozo Chikanari is born.
• Mid-1800s — The Aishi Precursor passed away.
• 1853 — After Japan resumed international trade, Shozo Chikanari began working at a dock in Nagasaki.
• 1854 — Sameba finds her Senpai. Oga Aishi is born.
• 1855 — Sameba's husband dies from an unknown illness, leaving Sameba with the condition for the rest of her life.
• 1863 — Shozo tried to open a shipping business, but it flunked when his cargo ship sink during a storm.
• 1865 — Kojiro Chikanari is born.
• 1872 — Oga finds her Senpai. Kijiyose Aishi is born.
• 1876 — Shozo borrowed money and land from the government and began designing building ships.
• 1886 — Shozo Chikanari founded Chikanari Dockyard, later renamed to Chikanari Heavy Industries.
• 1888 — Kanehira was born.
• 1890 — Kugi Aishi, her twin sister, Hiki and Isano Chikanari are born.
• 1894 — Due to the start of First Sino-Japanese War and demand of warships increasing, Shozo's company received a lot of business with Japanese military, which resulted in him becoming extremely wealthy.
• During the 1800s - One of the Aishi ancestors developed a psychological torture method that didn't involve physical harm. Instead, it used a form of hypnosis to make the victim believe they were experiencing extreme pain. This torture method wa used to turn their victims into obedient mind slaves and later will be passed down in the family.
• 1908 — Kugi and Hiki Aishi fall in love with the same boy, Kanehira. Hiki tries to compromise by suggesting both of them dating Kanehira while pretending to be the same person, but not wanting to share her Senpai with anyone, Kugi kills her sister and disposes of her corpse, later entering a relationship with Kanehira.
• 1909 — Kugi marries Kanehira.
• 1910 — Azebiki Aishi and Hodaka are born.
  • Throughout her life Azebiki researched the Aishi Condition by questioniong her relatives and studying her family history. Unfortunally, she only managed to trace the family history up to First Aishi. She used both scientific materials and occult books for her research, managing to find a number of consistent patterns and confirm various theories. She defined the term "Senpai".
• 1912 — Death of Shozo Chikanari. His son. Kojiro, inherits his business.
• 1914-1918 — World War I. Once again, Chikanari Heavy industries did a tremendous amount of business with Japanese military and made a lot of profit.
• 1915 — Masao Chikanari is born.
• 1919 — Hanzo and Arisa Aishi are born.
• 1927 — Hisho was born.
• 1928 — Azebiki found her Senpai, Hodaka. Even though she tried to resist the urge to spill blood, she initially gave in and killed her rivals and then confessed to Hodaka, who reciprocated.
  • After graduating from high school she entered a college for women with a strong scientific program. To keep her Senpai close, she made Hodaka work as a janitor in her college. After graduating she held various roles, including instructor, cytogeneticist, research associate, and, currently, a curator at a genetics museum exhibit.
  • Saisho Saikou, Hisho's future husband, is born.
• 1930 — Torahiko Yaginuma and Kataba Aishi are born.
• 1933 — Hisho begins her education at a private elementary school for upper-class girls.
• November of 1937 — Hanzo is drafted in Japanese military and sent to China.
• 1939 — Hisho attends a prestigious girls' secondary school, where she becomes fluent in both English and French.

The Second World War and Surrounding Events

The concept art of Arisa Aishi, who disguised herself as a soldier to protect her Senpai during World War II.

• September 1st, 1939 — World War II begins. Arisa finds her senpai. Her senpai is conscripted into the military to fight in World War II, so she begins working on a factory near his training camp and later takes the identity of a deserted soldier to join his unit. Hanzo starts helping Chinese villages that lie on Japanese army's path and performs various sabotage to delay the army together with Arisa. Eventually, Hanzo blows his cover but gets saved by Arisa before he gets executed. Together they flee to China, where for the next six years they participate in guerrilla war.
  • Torahiko's parents and little sister die during the war.
• 1942 — Kiyoshi Chikanari is born.
• 1944 — War mobilization. Hisho was drafted into wartime service, where she performed clerical duties for the military rather than engaging in combat or handling weapons.

  

  Official artwork of a 17 years old Saisho Saikou as an Imperial Japanese Army Soldier.

• 1945 — The U. S. military begins an operation to capture the Japanese island of Okinawa. Saisho Saikou participates in the Battle of Okinawa.
  • September 2nd – World War II ends. American military forces occupy Japan. Hanzo and Arisa are summoned to court in Nanjing to give testimonies against Japanese officers and soldiers who commited war crimes. After that, they return to Japan.
    • Due to Hisho's clerical experience and fluency in languages, she serves as the secretary to a U.S. Army general stationed in Japan.
    • Saisho actively helped rebuild Japan.
    • Torahiko was taken in by Japanese relief workers and brought to a temporary shelter in a repurposed school as a part of Japan's Ministry of Education program.
• 1946 — Saisho Saikou opens the first Saikou electronics repair shop and founds Saikou Corp.
  • Torahiko was granted placement in a public high school along with temporary housing.
  • Hisho enters University.
  • Japan's first tape recorder was invented.
• 1948 — Kataba finds her Senpai, Torahiko. She eliminates ten rivals and confesses to Torahiko after their graduation ceremony. Torahiko reciprocates.
  • Central Intelligence Agency assists Japanese police in investigating murders commited by Kataba.
  • Kataba gets arrested; Torahiko is summoned to police station for interrogation. Upon hearing about Kataba's crimes he begs police to give her a chance for redemption. A couple days later Kataba is offered a job in CIA in exchange for pardon of her crimes, and she takes the offer. She undergoes special training before starting her worknd getting deployed overseas.
• 1950 — Subaru, Dozuki Aishi and Arisa's daughter are born.
  • Kataba buys a house in Buraza, a small town outside Tokyo.
  • Hisho uses her family's riches to open a language school for Japanese women.
  • Death of Kojiro Chikanari. His son, Isano, inherits the business but immediately passes it to his son, Masao, due to old age.
• 1952 — American occupation ends. Hisho's business rapidly expands.
• 1954 — Saikou Corp produces the world's first transistor radio.
• 1955 — Hisho has developed national recognition as a young but extremely successful entrepreneur. Hisho leaves her business in the capable hands of her proteges and gets and becomes Saisho's secretary.
• 1960 — Kocho Shuyona and Beni Yoshida are born.
• 1961 — Saikou Corp produces the world's first compact VCR.
• 1964 — Kataba retired from her career.
• 1965 — Hisho marries Saisho.
  • Due to health complications, Masao Chikanari passes the business to his son, Kiyoshi.
• 1967 — Dozuki asks her mother for a basement. It takes a year for it's construction, which was done in secret.
  • Saikou Corp produces the world's first integrated circuit radio.

Before the Events of 1980s Mode

Entrance to Akademi Academy, the educational institution central to the events of Yandere Simulator.

• 1968 — The construction of basement in Aishi house in finished. Dozuki finds her Senpai, Subaru. Subaru is kidnapped by Kataba and then psychologically tortured by Dozuki. At some point, Dozuki starts referring to her husband as "Sureibu" (Slave).
  • Saikou Corp produces the world's first color television.
• 1969 — A man who later becomes an investigative journalist is born.
  • Saikou Corp produces the world's first compact cassette recorder.
• Late 1960s — Chikanari Heavy Industries had nearly withdrawn from the shipbuilding industry, and it had diversified immensely in differnt fields. This display, alongside their history of helping the Japanese government in times of need, was what made Saisho Saikou partner with Chikanari Heavy Industries.
• 1970 — Ichiko Saikou is born.
• 1971 — Main characters in 1980s mode are born:
  • January 1st — Kaguya Wakaizumi;
  • February 6th — Moeko Rakuyona.
  • March 15th — Honami Hodoshima.
  • April 20th — Sumiko Tachibana.
  • May 27th — Ritsuko Chikanari.
  • June 15th — Jokichi Yudasei.
  • July 2nd — Ai Doruyashi.
  • August 8th — Teiko Nabatasai.
  • September 1st — Sumire Saitozaki.
  • September 13th — Komako Funakoshi.
  • October 10th — Ryoba Aishi.
  • October 20th — Chigusa Busujima.
  • November 25th — Sonoko Sakanoue.
• 1972 — Rumiko Chikanari is born.
• 1975 — Arisa's granddaughter is born.
• 1976 — Ryoba's Sister is born.
• 1978 — Beni entolls in beauty school.
• 1979 — Ichirou Saikou is born.
  • Saikou Corp produces the world's first portable cassette player.
• 1980 — Beni graduates and recevies cosmetologist license.
• 1981 — Saikou Corp produces the world's first compact disc player.
• 1984 — Saisho Saikou orders the founding of an academy near Buraza: a new educational institution, named "Akademi." His daughter, Ichiko, takes part in designing Akademi, which was built accordingly to her preferences.
  • Saikou Corp renovates many buildings in Buraza, including Ryoba's house, for free.
• 1985 — Saisho Saikou successfully interviews Kocho Shuyona for the position of headmaster of Akademi.
  • Tsuma is born.
• 1986 — Akademi opens. Ichiko Saikou enrolls in Akademi and becomes the student council president.
• 1987 — Jokichi and Reiichi enroll in Akademi.
  • Reiichi ran for the position of Student Council president. He lost the election to Ichiko Saikou.
• 1988 — Ryoba enrolls in Akademi, where she meets her Senpai Jokichi. She was the only student who made friends with Ichiko Saikou.
  • Reiichi lost in elections again in 1988. However, Ichiko recognized his brilliance and made him the Vice President of the Student Council.
  • Due to Ryoba's growing closeness with Ichiko, Saisho Saikou began monitoring her, leading Saikou Corp to research the Aishi bloodline.
• 1989 — Ichiko Saikou graduates from Akademi. Reiichi becomes the school's new student council president.
  • Daigo is born.
  • Saikou Corp begins manufacturing portable electronic gaming devices.

Events of 1980s Mode

Official artwork for 1980s Mode depicting Ryoba Aishi alongside the eleven rivals she eliminated during her time at Akademi.

Main article: 1980s Mode

• April 1st, 1989 — Ryoba Aishi stabs Sumire Saitozaki to death in Akademi's third floor bathroom. Although Ryoba tried to deipose of evidence, a single bloodstain was found, which led to police suspecting that a murder could've taken place. Kocho Shuyona made a deal with police to make future investigations as confidential as possible.
  • An anonymous journalist begins patrolling Akademi's entrance in search for clues.
  • Ui warns the Student Council that she suspects Ryoba is a murderer. After that the council members start to be on high alert in Ryoba's presence.
• Week 1 — On April 7th, Kaguya Wakaizumi confesses her love to Jokichi Yudasei under The Cherry Tree and gets rejected, because throughout the week Ryoba sabotaged her rival's interactions with Senpai.
  • On afternoon, Ryoba completed Togo Atatsuma's task and met the Yakuza. Shee took a fake ID from the Yakuza to purchase mangas.
  • Ryoba meets Beni Yoshida.
• Week 2 — On April 10th, Moeko Rakuyona was burned alive after trying to put out a fire with a watering can in which Ryoba poured gasoline.
• Week 3 — On April 17th, Ryoba kills Honami Hodoshima by crushing her with a bookshelf.
• Week 4 — On April 24th, Sumiko Tachibana gets lethaly poisoned by Ryoba.
• Week 5 — On May 1st, Ryoba drowns Ritsuko Chikanari by pushing her into the swimming pool, putting sedative in her food beforehead.
• Week 6 — On May 8th, Ai was electrocuted on the gym stage.
• Week 7 — On May 19th, Teiko Nabatasai gets expelled from Akademi after Ryoba framed her for through alcohol, condoms, cigarettes, theft (stealing one of Himeko Dereguchi's rings), and cheating in that order for each day of the week.
• Week 8 — On May 22nd, Komako Funakoshi decides to withdraw for Akademi due to her reputation being ruined by Ryoba.
• Week 9 — On June 2nd, Chigusa Busujima confesses her love to Etsuji Odaka after Ryoba matchmade them during the week.
• Week 10 — On June 5th, Sonoko Sakanoue returns to Akademi to assist the journalist with the investigation. At night, Ryoba snuck into abandoned asylum to burn photos made by the evil photographer, as a mission for Sonoko. On the next day, on June 6th, Ryoba asked Sonoko to leave Jokichi alone, to which she agreed, considering the massive favor Ryoba has done for her.
• On June 16th, Ryoba gets arrested and brought to court right before she was going to confess to Jokichi.
• The trial begins. The journalist accuses Ryoba of murdering Sumire Saitozaki based on Ui Tunesu's testimony, but, in the end, Ryoba manages to defend herself: She is declared innocent. The trial got big coverage in national media; The journalist's reputation was ruined along with his career.
• Ryoba kidnaps Jokichi and locks him up in her basement. One day, after returning home Ryoba finds Jokichi missing and discovers a note from Saisho Saikou, talking about his people taking her Senpai and a "test" for Ryoba; for the time being, the details of this test are unknown.

After the Events of 1980s Mode

Official artwork of Ichiko Saikou departing Japan to find her twin sister Fun Girl, shortly after severing ties with Ryoba Aishi.

• 1989 — After unknown events, Ryoba marries her Senpai.
  • Eisaku Nonoshita dies after being stabbed by his victim who decided to take revenge on him.
  • There was no student council election at Akademi anymore, as no one wanted to run against Reiichi.
• January 1st, 1990 — Ichiko made her last call to Ryoba before escaping Japan and disappearing completely from public life to fulfill her plan of searching for her non-existent twin sister.
  • Kocho Shuyona decides to change the Akademi uniform.
• 1990s — Mae Kunahito gave birth to Genka in the 90s.
• 1994 — Ryoba's sister finds her Senpai, eliminates her rivals and marries her Senpai.
  • Saikou Corp starts producing game consoles.
• 1997 — Ichirou Saikou enrolls in Akademi.
• 1998 — Hodaka passed away.
• 1999 — Kocho Shuyona witnesses Ryoba meeting with Saisho Saikou.
• 2000 — Arisa's granddaughter immigrates to America.
• 2001 — Ichirou Saikou graduates from Akademi.
• 2002 — Arisa Aishi's granddaughter gives birth in America. She is the first Aishi to be born outside of Japan.
  • Kiyoshi Chikanari retires and passes the company to his daughter, Rumiko.
  • Rumiko falls in love with an unknown man, but Kiyoshi disapproves of their marrige. She and her lover have an illegitimate son they eventually marry.
• 2007 — Taro Yamada is born.
  • May 1st, 2007 — Amai Odayaka is born.
  • August 31st, 2007 — Osana Najimi is born.
  • An unknown woman falls in love with the journalist who accused Ryoba Aishi of murder in 1989.
  • Daigo's daughter is born. His wife dies shortly after giving birth.
• 2008 — Ayano Aishi is born on March 31st.
  • Megami Saikou is born.
  • Ayano's Cousin is born.
  • The investigative journalist's wife gives birth to a daughter. She dies during birth.
• 2010 — Kencho Saikou is born.
• 2012 — Kugi Aishi passed away.
• 2020 — The first American Aishi finds her Senpai.
• 2023 — Saisho Saikou steps down as CEO of Saikou Corp and appoints his son, Ichirou, to take over.
• 2024 — An urban legend about a mysterious hacker and information broker nicknamed "Info-chan" is born.
  • Taro enrolls in Akademi.
• 2025 — Ayano enrolls in Akademi.
  • Kokona Harukawa's mother dies of unknown cause, causing her family to lose a lot of money.
  • Mr. Harukawa takes out a loan from Rokuda Loans to pay for Kokona's tuition fees.

Events of 202X Mode

Ayano Aishi observing her Senpai from afar outside the Drama Club, as seen in the 202X Mode tutorial pre-cutscene.

• Before the events of 202X Mode — Oka Ruto re-opens the Occult Club.
• 2026 — The Saikou Family announces to the world that Saisho Saikou has passed away at the age of 98.
• During the events of 202X Mode — Ayano meets Taro Yamada, her Senpai.
• A few days before the beginning of the school year, Kokona Haruka asks Ayano to play the role of a murderer in a play. During the tutorial, Ayano learns about various methods of murder and disposing of evidence.
• After the tutorial, Info-chan contacts Ayano and tells her about Osana and her plan to confess to Taro on Friday. She offers cooperation and asks Ayano to make Osana suffer.
• Week 1 — On April 10th, Osana Najimi confesses her love to Taro under The Cherry Tree and gets rejected, because throughout the week Ayano sabotaged her rival's interactions with Senpai.
  • During the weekend Taro meets Amai Odayaka; Info-chan informs Ayano about new rival.
  • Kocho Shuyona has a call with Ichirou Saikou; they discuss possible bloodshed at Akademi in near future.
• Week 2 — Amai runs a bake sale to help her family's bakery.
  • Ayano eliminates Amai.
  • During the weekend Taro meets Kizana Sunobu; Info-chan informs Ayano about new rival.

Trivia

• The events in the Aishi timeline span over two and a half centuries, from the late 1700s to the 2020s.
• YandereDev has written a lot of backstories for many Aishi, but the fanbase will only learn about them if they ever get profiles on the official site.
• The majority of Aishi purposefully tend to stay out of the public eye, with the exceptions of one specific branch that became famous for their high-quality textiles.
• If YandereDev decides that it's canon that the 1st Aishi lived until age 122, this means that Kugi had opportunities to interact directly with the First Aishi up until she was 12 years old, and was able to pass on firsthand knowledge of the Aishi Condition straight from the First Aishi up until her death in 2012.
• After 1900, the average Aishi has a very long lifespan. Many of them live to be past 100, with one even reaching the age of 122.
  • No Aishi has lived past 122.
• Azebiki Aishi is the oldest living Aishi. She has more knowledge/insight into the Aishi Condition than anyone else. At family gatherings, she is happy to share her knowledge with younger Aishi who seek to understand their condition.
• Despite being fictional, the timeline incorporates real historical events such as World War II and the U. S. occupation of Japan.
• Kataba Aishi is one of the only known Aishi family members to work with foreign intelligence agencies.
• Saikou Corp's timeline mirrors real-world Japanese tech history, with inventions like color TVs and compact cassette recorders released in the same years.
• Dozuki Aishi is one of the only Aishi who has never taken a human life. Instead of eliminating rivals, she simply mind-broke her Senpai.