Board Thread:Questions and Answers/@comment-27229742-20151012232843

https://twitter.com/YandereDev/status/647799558961950720

It says here that if Senpai is female, then the Imouto will remain female.

https://twitter.com/YandereDev/status/652655496168521728

Here, the dev calls Senpai's Sister, the "Default Imouto" and "Senpai-chan". The first nickname implies that we can change her appearance. I didn't hear him call any of the other rivals default something, so is changing Senpai's Sister's appearance a special thing? I've heard that you will be able to customize the female Senpai. The female Senpai looks like the Imouto. The Imouto's second nickname given is "Senpai-chan".

So is the Imouto the female Senpai or not? The first link seems to disprove that idea.

Female Senpai idea: https://twitter.com/YandereDev/status/639934675989884928

Not-quite-for-certain-but-still-posted-by-dev art of Imouto: http://vignette4.wikia.nocookie.net/yandere-simulator/images/2/2e/DefaultSister.jpg/revision/latest?cb=20151010094349 