Season 0 of OniAi premiered on December 26, 2012.

Season 1 of OniAi premiered on October 5, 2012.

After 6-years' separation, Himenokouji Akito reunites with his twin sister Akiko and they live together once more. However, in the interim, Akiko had developed a serious case of bro-con, romantic feelings for Akito. It doesn't stop there as Nikaidou Arashi, the student council president of his new school, vice-president Nasuhara Anastasia, and Sawatari Ginbei Haruomi, who followed Akito all the way from Kyoto, all move in with him one after the other.