Osana Najimi

'''Osana Najimi is a planned first rival for Senpai's affections and will be used as a tutorial at the beginning of the game. She is a student at Akademi High. '''

'''NOTE: The character who stands under the cherry tree is Rival-chan. Osana in a future update will be completely different.'''

She is not active yet because YandereDev wants to give her a different character model to make her more unique, but her character model is not compatible with all of the animators that were made for the other female skeleton that the rest of the females have. Osana can't be put into the game unless a character rigger makes a control rig for her and an animator uses this rig to create a full set of animations for her, or if YandereDev gives her the same character model and animation as all of the other female students.

The downside of giving her the same character model as all the other female students is that she will look like a clone of Yandere-chan, but with different eyes, hair, and stockings. So far, YandereDev can't find anyone to get it done. It may be a while until she is implemented without a whole bunch of Osana-specific "event" animations as well.

YandereDev also has mixed feelings about Osana. Her current design is super cute, and does not suit his opinion of tsundere characters. To balance this problem, he would either choose a personality that suits her cutest appearance, change her design so that it suits her tsundere status, or split her up into two sisters, a childhood friend and a tsundere childhood friend. He doesn't like the third solution too much because the death of one sister might affect the other so strongly that she couldn't consider dating.

Appearance
Osana's original look had golden/brown eyes and her hair in two golden pigtails. Her hair was tied up in two plump scrunchies and she had a purple bow on her head. She wore white leg warmers.

She is getting an update with long, orange twin tails that reach her thighs. The ends of her hair have a small yellow gradient. Her hair will be tied up in thin pink scrunchies with white polka dots, and she will wear salmon socks with white polka dots. Her shoes are black. On the reference picture of Osana, a small red bow can be seen on her head. Only the back of her was shown, and this quick glance can only be seen in "E-mails, Volunteers, and Progress" This character was also in a small cameo in one of YandereDev's videos, "I Want My Senpai Back" She was the main antagonist of the video that stole Yandere-chan's Senpai. The tsundere was later killed off in the end of the video by being stabbed to death 37 times.

Scenes
In the original introduction of the game, after Yandere-chan bumps into Senpai, she can be seen talking to him, acting like a stereotypical tsundere. You can see the first intro on YandereDev's YouTube channel., but this is now very outdated.

In the second intro added in the August 15th, 2015 Build, Osana is mentioned by Info-chan as she requests that Yandere-chan murder the girl. Info-chan expresses that she wants Yandere-chan to "make her suffer". It is unknown what Info-chan has against Osana.

She appears in the spin-off game Yandere Clicker. Her face was used for the "Imouto" option, described as "A kawaii Imouto who will stab Senpai for you". However, she is not Senpai's little sister and should not be mistaken as such. She also makes a small cameo in the "April Fools' Trailer" with her photos appearing on the cork board. Knives through Osana's head held the photos up.

Personality
Osana Najimi is a tsundere, which is a person that is very sweet, kind, and cute, but projects a hostile attitude to those around them, often only towards their love interest. It's not very likely that Senpai would know about her crush on him, as she repeatedly insults him and seems oblivious. Regardless of Osana's rudeness and Senpai's ignorance, Osana is still very considerate. In the original intro, she is shown walking Senpai to school.

The second intro gives no indication of her personality, but "I Want My Senpai Back" makes her look like a tsundere, so she might be tsundere.

When you scroll through her animations, she looks a bit girly with the way she poses, suggesting that she has quite the feminine side.

She may not be a good friend, considering that if you get rid of her non-lethally and Senpai's sister dies, she will not go back and comfort Senpai.

Senpai
They were childhood friends in the first intro. Osana has a crush on him, although he does not seem to be aware of it. The first opening shows Osana and Senpai together, and even walking to school with each other. Osana yells at Senpai, but they still seem close.

In the second intro there is no information about what their relationship is now. Osana still has a crush on him though and will still confess her love to him on Friday.

Yandere-chan
Osana Najimi is a target of Yandere-chan because she is a rival for Senpai's affections. In the first intro, Yandere-chan has qualms about killing others. She simply wanted a love life and Osana was in the way, but Info-chan, a glory-hungry journalist, gives Yandere-chan the idea to kill Osana.

In the second intro, Yandere-chan already wanted Osana out of the way, by any means necessary. Info-chan just encouraged her more and gave her some info.

Info-chan
In the first opening, Info-chan didn't hold anything truly personal against Osana. Still, it is now known that back then Info-chan was the main antagonist who was going to be a rival for your Senpai, as seen on Info-chan's page. It is also known that in the original intro Info-chan wanted some terrible events to unfold at Akademi High to boost her newspaper sales.

In the second intro it is not stated why Info-chan is going against Osana. Info-chan simply wants Osana to suffer, though anything about being a journalist is never stated.

Trivia

 * YandereDev has said that Osana Najimi is "Tsundere-chan with an actual design that had effort put into it."
 * Osana Najimi's name is a pun on "osananajimi," a common trope in the romance genre which means "Childhood Friend" in English.
 * In the video "I Want My Senpai Back", Osana is voiced by Brittany Lauda, who also plays Audrey from the popular adult game HuniePop.
 * She is the first official rival to be introduced.
 * She is the first tsundere character to be introduced by YandereDev, the second being Tsundere-chan from Kuudere Simulator.
 * In the final game, Osana will tease Senpai about how he stands under the cherry blossoms all day, a reference to how long Osana was under her cherry tree.
 * Osana's hair cannot be loaded by any other female NPCS.
 * Currently, Info-chan won't give you information about her due to not recognizing her placeholder model. She is not killable or interactable yet.
 * It is implied on Twitter that Osana's birthday will be in January, most likely the 1st.
 * Osana is the only canon character to have "Tare" eyes, aka "Puppy eyes". (This only applies to her current in-game model, in YandereDevs's new design her eyes are "Tsuri" aka "Cat eyes")