I never understand why she is portrayed as a “child” character most of the time when her design is like this lolNever Forget Miwa has The Biggest Bust between the Sisters
Judging by the incredibly hot face he made completely innocently, I don't think Miwa really wants Yuu to "become an adult".
The minute he "awakens" will be the moment she, her sisters, and every female in a three kilometer radius become pregnant.
Yuu thinks he is useless. The girls, the people he is closer to than anyone else, think he's pathetic and no one else could like him. Until his self image changes he won't be able to consider the possibility the girls could like him romantically.MC was raised by an abusive mother, has a ton of life skills... but the mentality of a 5 year old.