Imouto wa Gal Kawaii

It is an anime adaptation of Wakatsuki Hikaru’s Light Novel.

Following the remarriage of his father, Shouhei Shindou finds himself living with his new sister, Rino Mizusawa. However, even though the latter seem to have a relationship between ordinary brother and sister, Shouhei is secretly attracted to Rino.

One day, Shouhei takes the opportunity to find himself alone in the toilet with his sister to try a rapprochement.