where can I find Oto`s Story? i dont remember him T-T
He is Michi's dad (= oto-san). Michi is a little blond kid who is Hikari's friend. They start appearing in the third volume. As the story progresses we learn that "Oto" is an Omega and deeply distrustful towards alphas. He nearly stopped all contact with Masaki and the kids when he learned that Masaki is married to an alpha (Hiro).
Is there a big brothers story?
There he is RAITA ~
http://www.mangago.zone/read-manga/akuma_ni_kiss_wo/
I have a feeling Saras connected to Rens deceased friend.