Responses
She said the dad has wildcat blood. http://www.mangago.zone/read-manga/nekoka_danshi_no_shitsukekata/mh/v05/c025/pg-21/
I caught that bit. But lions are technically wildcats. :/ And he also specifically told Michiru in a call that he and Shiou are lions. Also, a lot of people here are insisting they were not siblings due to Michiru's cat form. And the characters themselves had their doubts. Oh well. I am not gonna dwell on it. I am eagerly waiting for the extra chapters though...
It seems mama is adamant about not cheating. So maybe mama has some cat genes somewhere she didn't know about. (⊙…⊙ ) I don't even really know anymore. But it was a touching ending. Also, Kagetora and Kuroe. OMG.