My inner fujoshi tell me that you are wrong for me blond hair-san is the seme and black hair-san is the uke (≧∀≦)
I also agree with op. The thing is the black haired guy says "when this guy smiles, he's-"
Before getting cut off. Based on the structure and common yaoi knowledge I think he was about to say "cute".
For whatever reason, blonde soft hearted delinquents are always bottoms in yaoi, I'll be pleasantly surprised if it's different in this one. Or since it's shonen ai, they could just leave ambiguous by ending when they kiss.
just like you say it's shonen ai so we will probably never know (≧∀≦)
My inner fujoshi tell me thats the black hair is the seme.. and blond is the UKE but i don't like it!! Im kinda sure about my hypothèse cuz i had never been wrong in guessing which uke or seme in my life.... and thats seems Clair thats the blond hair is the uke....!! I wish if he is not the uke i wanna see him.as SEME please can you beautiful people updated and don't froget about this manga