This boy is literally fifteen goddamn years old. He doesn't know the first thing about being a human being, let alone the rest of the world. He's weak, inexperienced, hard-headed, and worst of all, he has the 'hero' tendency without the skill, stats, and equipment to pull it off.
Anyone who's in guardianship over this boy will see he is a suicide-by-adventure case waiting to happen. They can say he's legally an adult all he wants, but that doesn't mean he actually is. But, this is manga, so the writers have him more mature than he should be given his upbringing, with wisdom to match, and knowledge he shouldn't possibly have.
@newprimus
That's only a consideration when the subject has all the rest of a society to compare their own experiences and family to. The 'desire for the unknown that I can just barely make out' kind of deal, to put it in anime-esque terms. Raised in a vacuum, all he will know is what his mother teaches him, and all he will know is that when she takes care of him, it makes him feel good. Absolute Reward in a vacuum, his neurochemistry would essentially punish him for thinking of giving that up past a certain point.
But, again, this is a manga, so he'll have none of those issues. He's always right in the end, she's meant to be wrong and for some reason every Asian comic shows any sort of 'aggressive woman' to be something to be feared and cast aside, not embraced or taken seriously.