The Yandere Sister Is a Bit Cold

Quite realistic. The male protagonist has pure affection for his adopted sister, but unfortunately, the adopted sister is in love with the male protagonist. The male protagonist has always been particularly disgusted with his adopted sister's feelings. I don't know whether the end of the last sentence means that the male protagonist is letting go of the past or that he doesn't want to live anymore.

It would be great if my sister was the heroine

Damn, your girl is so fucking sharp

Okay, it's very interesting. It would be great if this book was published.