S1·E12 Farewell, Hiyori-chan

Mitsuki's his little sister, and Yukina is an older sister figure. To Yuuya, both of them are precious "family members". But on one morning of their stay at the hot-springs, Neko hypnotizes Yuuya to "be more honest", and he calls Mitsuki "really cute" and gropes Yukina's breasts.