Ren'ai Made Sentakushi Hitotsu

Riku and his childhood friend Misora loved each other, but she passed away in an accident when they were in grade school. Ever since then, love has become a trauma for him and he did everything to never have the same kind of relationship with another girl again. He treated his childhood friend Kirio like one of his guy friends. He considers his lady co-worker Yukari as a rival. Misora’s younger sister Suzuho, who’s quite attached to him, is like a follower to him. His younger sister Karen seems to hate him. He continued to live his normal life without looking at them as women. However, one day, a girl who looked exactly like Misora appeared before his eyes. He suddenly became aware of his feelings, and so did all the other heroines.

[From Hau~ Omochikaeri!]