Hanako Yamada

'Senpai's little sister will be either the 8th or 9th rival in Yandere Simulator''. She has not been fully implemented into the game yet.'''

She is a student at Akademi High. She is one year younger than Senpai, but is two school years behind him. She will remain female, even if there is a female Senpai.

Appearance
Senpai's Sister will wear the default female school uniform, unless customized by the player.

She will look like a gender-swapped version of Senpai, which means that if Senpai is customized, she would have the same skin and hair color as him. However, the little sister will have a unique hairstyle that no other NPC will have. At one point, it was made to look similar to Midori's original hairstyle, except that she had more bangs on her face.

Around November, her appearance was changed again. If Senpai is kept as default, the sister will have black hair and black eyes. Senpai's sister now has two pigtails that reach her shoulders, similar to the first drafts of her appearance. She has a pink heart hairpin on the top right side of her hair. She has fair skin and light grey sneakers.

It is also known that she will eventually wear special stockings to make herself stand out, as well as unique panties that suit her personality.

Personality
Senpai's little sister was originally going to be cute and innocent, but she was later changed to lewd, jailbaity and super perverted. Because of these changes, the player would feel less guilty if she was killed.

After that she was changed to extremely clingy, childish, and emotionally dependent on Senpai. She will be a "happy anime girl". She cannot participate in physical fights against murderers.

Routine
His sister will remain in another city until the week when she is introduced. Since she will always be close to Senpai, it is presumed that she will have a similar routine to him. In order to eliminate her, the player will have to find a way to eliminate her during the few moments she is away from Senpai.

If the player fails to eliminate the sister by Friday, she will force Senpai to promise to not get a girlfriend by the Confession Tree.

Senpai

 * Main Article: Senpai

Along with Osana, she and her brother used to play together when they were little.

She doesn't lust after her brother. She loves her brother to the extent that she does not want him to get a girlfriend. She wants all his attention. She is also extremely clingy, possessive of him, and would never want to leave his side.

If she is killed, Senpai's sanity variable will greatly decrease.

At the end of the sister's week, she will force her brother to agree that he'll never get a girlfriend.

Osana Najimi

 * Main Article: Osana Najimi

Osana, Senpai and his sister used to play together when they were little.

Suitor
In the future, Yandere-chan will be able to matchmake Senpai's Sister with her suitor. She will have to make the sister love the boy even more than she loves her own brother.