@Spawn7586 - you've been watching too much anime. Anime children usually behave a lot younger than children of their age should.
By the end of kindergarten, children are fully capable of speech. And reasoning too. They're just uneducated. And Ami and her friends are already in elementary school.
Fucking christ why is this plotline even in this manga, its fucking disgusting and feels so out of place to the genuinely adorable other couples. The only thing its good for is making Rina and Hirofumi's age difference feel fine.
well damn... I thought it was just a running gag that was misunderstood, but homeboy is a legit lolicon. That's one way to kill your character I guess...