I'm rather conflicted on this matter. When I saw Bun-chan here: http://www.mangago.zone/read-manga/ichi_ni_no_san/sa/sa-c002/33/ I was like "Yup, that boy's an uke for sure" but then I saw him here: http://www.mangago.zone/read-manga/ichi_ni_no_san/sa/sa-c003/8/ and thought, "Damn, he sure would make one sexy seme. I mean, just look at that body!" So yeah. It could go either way at this point, I think. Maybe they could even be a reversible couple...? Probably not, but you have to admit, that would be nice!
hmmm, to me he seems like seme. Bun-chan seems like he would be overpowered by choco.
Maybe I read too much yaoi but Choco feels like an Uke to me xD