Kono Koi to, Sono Mirai.

Summary

Shirou Matsunaga has been subject to irrationally cruel treatment by his treacherous three sisters. Seeking an escape from this hellish existence, he enrolls in a boarding high school. There, he meets Mirai Oda, his new roommate. Mirai, suffering from gender identity disorder, has the body of a woman, but the soul of a man. Mirai had investigated Shirou's circumstances beforehand, and in order to secure his own safe co-existence, chose him as his roommate. Shirou tries to make the best of this situation, but as the two of them spend more time together, he finds himself unable to avoid becoming attracted to Mirai... (Source: Sugoi Japan)