the hayase's had other members they probably cut the primary bloodline and go with a secondary one, so she is more like a great great great niece(or cousin) to kahaku
and in the end they are all hayase's reincanations thats why they look similir and had mostly the same personality, and yes kahaku was the only of hayase's forms that actually learned how to love fushi at the end, withc i wanted to at less had an eetc in their next incarnation but seens that mizuha is all hayase and nothing like kahaku
Maybe hayase only "fully" possess female descendants. At the first time only kahaku that said he isn't really interested in fushi bcs he's straight until that immo took parona visual.
But parona body vomit when kahaku tried to kiss fushi. Maybe he feel devastated when saw that? So he treat fushi more "humanly" and began to love all of fushi visual compared to his ancestor that makes fushi as her reproduction tools.
Only kahaku that has rationality, tiny bit of right mind, and moral compare to hayase and all of her descendant. Too bad he killed himself to protect fushi. BUT WHY HAYASE BLOODLINE STILL CONTINUE WHEN KAHAKU DIED? IS HE SECRETLY MAKING LOVE BEFORE DIE OR WHAT. I have had enough to this serial psycho