Oneechan ga Kita

Oneechan ga Kita (お姉ちゃんが来た, Onēchan ga Kita, lit. "My Big Sister Arrived") is a 4-panel manga series by Rikō Anzai, serialized in Takeshobo's seinen manga magazine Manga Life as well as sister magazine Manga Life Momo since July 2011. It has been collected in four tankōbon volumes as of November 2014. A 12-episode anime television series adaptation by C2C aired between January 8, 2014 and March 26, 2014. A thirteenth OVA episode was included in the first Blu-ray volume released on March 22, 2014.

Plot
The story revolves around Tomoya Mizuhara, a 13-year-old boy who suddenly gains a big sister when his father remarries. 17-year-old Ichika is a little strange, and her affection for Tomoya is rather overwhelming, if not scary. On top of things, Ichika's friend Ruri is the ultimate sadist. Then there is Ichika's big-breasted quarter-Japanese friend Marina.