>>537013775
Nono, you clearly mean his grandpa, Genzou Narahara. The one that made Rokuhara abandon his Narahara surname when he found out he was born of a gay sex mistake with a certain mercurial traveler. Hence why we now know him as dr. Rokuhara, but as we all know he could not fully escape his genes, and like mpreg father, like son...
seems we got sidetracked a bit.

>>534173061
Rokurius created Rokuhara because he loved Karen, but could never be with her, both emotionally and physically.
Karen’s curse (Curse of Promiscuity) causes her to be highly sexually active to the point of being a dangerous sex beast and will cause death if not sexually sated.
Since Rokurius couldn't sex her without being drained to death, Rokurius created Rokuhara as someone who could survive her sexual urges, love her, and be loved in return.
Rokuhara was made:
To be Karen’s equal.
To give her the connection Rokurius himself could never have.
And to break the endless cycle of sex with others Karen was trapped in.
In the end, Rokuhara becomes Karen’s partner, something Rokurius always wanted, but could never be.