Well... I think that is a form that the mangaka show how Shou see his lover... like something so cute that makes he go crazy... (≧∀≦) or maybe the mangaka is just showing how Hisashi is inside (=・ω・=)!? I don't know but it's funny. (●'◡'●)ﾉ
I think it's how Hisashi is on the inside. Sweet and innocent, which is why Shouta is having such a hard time romancing him
I agree with the other two people that it seems like it's what Shou sees him as but I too was frustrated wanting to see the "real"Hisashi. I'm glad we can see him a lot more in the Itoshi Akuma series where he's the friend!
I find it really annoying that Hisashi is drawn as a chibi 90% of the time. It's like Shou is trying to romance a toddler. I'm not even exaggerating with the 90%, he goes pages without looking normal once. Hisashi has a decent character design so why the stupid chibi art style? Is the artist just being lazy?