“Does it matter what we’re doing now? Whatever the reason, we’re still siblings in the family.” My little sister, Kururi, is a brocon to the extreme. Whenever our eyes meet, she’s so attached to me, always crying to sit on my lap or hold hands with me. “Hehe. Onii-chan, I love you!” Kururi smiled mischievously, at night, she entered the same room as me. During dinner, our parents revealed a shocking truth to me, which even Kururi herself didn’t know. “Kōsetsu-kun and Kururi-chan are not related by blood.” Wait, Kururi and I are stepsisters!? That would be a bad thing… “If we weren’t siblings, that way, I could marry Onii-chan!” My little sister was always the type to say things like that! The relationship between a serious older brother and a half little sister who is affectionate as a family begins to change with this hidden secret!