Bishoujo Mangekyou -Tsumi to Batsu no Shoujo-

Yuuma was forced to take a hiatus from school due to unspecified circumstances that left him hospitalized.

After a year apart, he finally reunites with Yuuri, his breathtakingly beautiful twin sister, and they start living together. Nonetheless, Yuuma harbors a secret that he can never share with her - he's head over heels for his own sister...

As the truth inevitably comes to light, the love becomes an obsession that threatens to swallow him whole...

Translated and edited from the official site