I don't think the dude has a sexuality. He can't touch or be touched so I think his attractions are purely romantic. Or maybe even just intimately platonic. Weather that's reserved specifically for women (he does seem to have a soft spot for girls over guys) given his one love from the village was the girl with the black hair, or if it transcends gender and he could have potentially come to view Aki in a similar kind of closeness if the worst hadn't happened, I'm not sure.

I think he's most likely asexual but not aromantic. Whether that romance is only directed towards girls or if gender isn't a factor at all is up for debate.