Yaku Zaishi is one of the male students who currently attends Akademi.
Appearance[]
Yaku has short, slicked-back gray hair with light green streaks in it. He has green eyes, which are revealed if the Science Club disbands.
He wears the default uniform with a metal visor that displays his emotions through green pixels that take the form of different eyes unless customized by the player. When in the Science Club, he will wear a white lab coat. If the Science Club disbands, he will take off his visor.
If Ayano kills him, his visor will have X-shaped eyes on it. If he is being bullied or has lost a teacher's trust, his visor will have sad eyes.
His visor displays his emotions, since he usually does not express his emotions much.[2]
According to YandereDev, Yaku isn't strong nor attractive. As he is a nerd for science, he isn't physically fit. He also hides most of his face with a visor, so effort to his appearance isn't applied a lot. Not a lot of girls in his school consider him "cute".[3]
Personality[]
Yaku Zaishi is a chemist who is obsessed with combining various chemicals to observe the results. He is less accomplished than his peers, and is vague and evasive whenever he is questioned about his intentions. He is single-handedly responsible for the majority of noise complaints at Akademi, as his chemical experiments have been known to result in loud explosions. His head-mounted device is capable of detecting and displaying his current emotions, which have been observed to change at the drop of a hat. He is a big fan of anime and video games, and is constantly attempting to convince his peers to indulge in his hobbies.
A young chemist who is obsessed with combining various chemicals to observe the results. Vague and evasive whenever he is questioned about his intentions. His head-mounted device is capable of detecting and displaying his current emotions.

Yaku looking suspiciously at the camera.
Among the personas that are currently implemented in the game, Yaku is a Teacher's Pet. He will give Ayano Aishi a suspicious look if she aims her Phone at him. If he sees a corpse or witnesses a murder, he will run to the Faculty Room and report the corpse to a teacher, unless another Teacher's Pet already has. He cannot participate in physical fights against murderers.
He is mostly a loner, but tries to be friends with Horo.[4][5]
Yaku does not pry into the personal matters of other people.[3]
Routine[]

Yaku mixing a variety of chemicals on this table to get a reaction out of them.
At 7:00 AM, Yaku enters the school grounds with the other members of the Science Club. He walks to the Locker Room at 7:05 AM and changes from his outdoor shoes to his indoor shoes. At 7:15 AM, he walks to the Science Club on the Third Floor and combines different chemicals together.
At 8:06 AM, he walks to Classroom 2-1, sits at his desk and plays on his phone. He starts his morning classes at 8:30 AM, and leaves eat his lunch outside the Science Club 1:00 PM.
He walks back to class at 1:30 PM and participates in cleaning time between 3:30 PM and 4:00 PM. At 4:00 PM, he heads to the Science Club and stays there until the end of the day.
If the Science Club is disbanded, Yaku will socialize with the other former members in the Science Lab during periods in which he would normally attend it.
Topics[]
The Conversational Topics Yaku has opinions on are as follows:
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Positive | Negative |
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Relationships[]
Science Club Members[]
- Main article: Science Club
Yaku and the other Science club members are simply acquaintances. While they don't hate each other, they aren't friends.[6][7]
Horo Guramu[]
- Main article: Horo Guramu
Yaku and Horo have been friends for over a year. Within the first week, the two of them talk during lunchtime about the anime; "Magical Girl Pretty Myuki". With Yaku trying to convince Horo to give the show a try and what it's about. Horo was hesitant at first especially with most of the plot points being "too obvious". He does grow to like it, but not the way Yaku wanted him too.[6][7]
Others[]
His Family
Yaku doesn't like his family much as they think he is a freak, weirdo, and a mad scientist.[8][5] He plans to move out of his home after he graduates Akademi.[8][5]
Sakura Hagiwara
- Main article: Sakura HagiwaraIf Yaku and Sakura Hagiwara went on a date, they'd both be extremely shy and bashful.[9] Additionally, if the topic of Sakura's medical condition came up in a discussion, he would want to ask her more questions to see if he could devise a cure.[3] However, she would not fall in love with Yaku just because the latter developed a cure to her disease.[10]
Trivia[]
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- He was implemented as a silhouette in the May 10th, 2018 Build.
- He was fully implemented in the July 1st, 2018 Build.
- His name, 'yakuzaishi' (薬剤師), means 'Pharmacist/Chemist' in Japanese.
- After the removal of the Rainbow students, the conversation between Sota Yuki and Haruto Yuto has been moved to Horo Guramu and Yaku. Yaku now has Sota's voiced lines.
- The player can see him commenting on Hoshiko Mizudori's phone.
- Due to Nagaharu Kurudo being removed and then returned to 1980s Mode, Yaku is the only student with slicked hair, used when matchmaking Riku Soma with Kokona Haruka.
- His voice actor, Nathan Sharp, is a musician on YouTube.
- Yaku started watching Magical Girl Pretty Miyuki since it first aired on Television.[6][7]
- Yaku's visor was built by Kaga Kusha. He requested for two reasons. He isn't very expressive and doesn't convey his thoughts or feelings with his face. So he wanted to have a head-mounted display that would let others know his actual thoughts and feelings.[8][11]
- Yaku loves to create his own food. With his knowledge of chemistry, he is able to synthesize pills and liquids that contains all of the vital minerals and nutrients to create a food that a human would need to survive. The end product will come in bar form, and look more like an ice cream sandwich.[8][11]
- His favorite color is green.[4][5]
- He first joined the Science Club on the first day of the school year, or orientation day.[9]
- Yaku's type in a girl is someone who shares his interests, which is anime.[12]
- The one thing that Yaku does when he is home is science experiments.[3]
- YandereDev imagined if Yaku put effort in his fashion taste and appearance, he could surprise a lot of people by turning out to be more attractive than they suspect.[3]