I feel the same. I think that even if one person is the reincarnation of the other, it doesn't mean that they are one and the same. For me, they are entirely separate and different beings. I lost some love for the story once I found out that Ono is Kayo's reincarnation. I wanted Hisa to have fallen for Ono because he is Ono, not because he was once Kayo. And, it's sad that Chizuru has to live with the fact that each time he is with Ono, Ono will be reminded of Hisa.
Hmm...For some reason I saw that in different way. I kept thinking the same thing until the last page, but do you see this ---> http://www.mangago.zone/read-manga/jigoku_meguri/mf/v02/c005/20/? Ono said "What I feel for CHIZURU is surely love". He didn't use "Kiyo", so he was certain he loves Chizuru for who he is (and that part made me cry). So yeah, it's heart-wrenching...He keeps Kiyo in his heart as a true love, but now he loves Chizuru because he is Chizuru.
Well, that's just my opinion, but that's the way I see this story (=・ω・=)
i see nothing wrong with it. in the beginning of the story its clear they are drawn to each other and fall in love quickly. enma was only brave enough to open himself up to love again, when he knew he had met him again in them lifetime. they were drawn to each other again in the end. i find it really romantic.

I don't really like the reincarnation plots. I find them really cruel. When Enma confess to Ono it's because he knows he's Kiyo's reincarnation. And then, when Ono meets Chizuru he keeps calling him Hisa. Yeah, he's Enma's reincarnation, but... isn't that cruel? This kinda stories make me suffer because it looks like you can't love a new person just for who them are, and only because they once where the one you loved.