All that in a manga based off of a children's game?
Damn, when they say hentai, they mean hentai
Originally mangas like those targeted teens & adults. One instance of this is One Piece where characters speaks in a profane languages, smoke cigarettes & drink booze.
most mangas focus on a more mature audience so thats all fine to find in a manga compared to say a book for primary school aged kids.
most kinds reading this stuff dont get the themes we all pick up which many people forget too so there's no harm in them being there.