Osana Najimi

'''Osana Najimi is the first introduced rival[5] and a student at Akademi High. She will be used as a tutorial at the beginning of the game.[6]'''

She was going to be implemented within several months (as of January 11, 2016) according to Druelbozo.[7] YandereDev first needs dozens of male and female animations for Osana to be implemented.[8]

It should be noted that the character who stands under the cherry tree southwest of the plaza is Rival-chan. The original design for Osana had Rival-chan's appearance, but YandereDev thought she didn't look "tsundere" enough. There is now a new appearance for Osana. Rival-chan is the student with the original model, who is now considered a different character.[9]

Osana's original store-bought model was not active because YandereDev wanted to give her a different character model to make her more unique, but it was not compatible with all of the animations that were made for the female skeleton that the rest of the girls have. She couldn't be properly implemented unless a character rigger made a control rig for her and an animator used that rig to make a full set of animations for her, or YandereDev gave 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 would look like a clone of Yandere-chan, but with different eyes, hair, and stockings. YandereDev could not find anyone to rig or animate her original model,[10] so it is possible that this will be the case. Even with the old model out of the way, it may be a while until Osana's new model is implemented, because YandereDev does not want her added without also putting in a whole bunch of Osana-specific "event" animations.[P11]

Personality
Osana Najimi is a tsundere, which is a person that is very sweet and kind, but projects a hostile attitude, 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 he seems oblivious. Regardless of Osana's rudeness and Senpai's ignorance, Osana is still very considerate. In the original intro, she is shown walking with 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 is still likely to be a tsundere.

Osana may not be a good friend to Senpai, considering that if she is eliminated non-lethally and Senpai's sister dies, she will not go back and comfort him.[14]

Routine
Though it is unknown at the moment, YandereDev has said that her routine will put her in close proximity to Senpai or other students.[15]

Senpai
They were childhood friends in the first intro. Osana, Senpai, and Senpai's sister all played together when they were younger.[16] 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.

There is no information about their relationship in the second intro. Osana still has a crush on him, though, and will still confess her love to him on Friday. However, if Senpai's sister dies and Osana is eliminated peacefully, Osana will neglect Senpai, so she probably doesn't care that much about him.

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 wants a love life and Osana is 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 wants Osana out of the way by any means necessary. Info-chan just encourages her more and tells her about Osana's plan to confess to Senpai.

In the "It's Beginning To Look A Lot Like Murder" video, Yandere-chan mentions that Osana is "flirting" with Senpai "again". This may indicate that Osana's tsundere demeanor is a way of flirting with Senpai, but it's also possible that this is just how Yandere-chan interprets her actions.

Info-chan
In the first opening, Info-chan didn't hold anything truly personal against Osana. However, she was once the main antagonist and was going to be a rival for Senpai.[17] The original intro also shows that Info-chan wanted some terrible events to unfold at Akademi High to boost her newspaper sales. Her motive for wanting Osana dead might have been one of the two, or both reasons, depending on when Info-chan being the main antagonist was changed.

The second intro does not state why Info-chan is going against Osana. Info-chan simply wants Osana to suffer, and anything about being a journalist is never stated. There isn't even a Newspaper Club at Akademi High anymore,[18] which makes it unlikely that her motive is wanting her articles to be popular.

Senpai's Sister
Osana, Senpai and Senpai's sister played together as children.