["i don't know but i think yuu have some interest in girls, at least in the anime, even if it's tiny. I don't believe when people say he is asexual. He blushed around shinoa after saving her and when she was wearing her new uniform. Also after mitusba and shinoa came out of the shower so there is that."
"A compelling point noted! As you and those in favour of Yu and Shinoa can observe, there is at least something there."
"In reality the yuu in manga is shown rather uninterested by both of them romantically. It shows that the main subject of this manga is family love, and romantic love is just one sided."]
Obviously the "lack of inclination from Yuu's part" is more about a way for the creators to open room for more drama and create tension in the story, in what is a very obvious love trinagle between the characters. Than a proof of a "sexual identity" of the main character.
I'll never understand the little nitpick bits, that some people choose to bring up as "proof" of this thing or that thing, than paying attention to the overall whole of the story as the real proof.
You have 2 characters, one is a girl, and the other one is a boy, and both of them have strong feelings for the main character.
Is not really that different from the typical love triangle of two girls one guy, or two guys one girl done to death in many anime stories.
I think is just some people who is uncorfortable to the idea of bringing both genders into the classic equation, than the creators not making enough remarks of tension between the characters.
Yes, the story doesn't focus on romance, but that doesn't mean that "Yuu and Mika" or "Yuu and Shinoa" "moments" are mere accidents or people just making wishful thinking. They are there, and they are intentional.