Not sexual at all.
Impressions:
I think if you want this setup to work, you need to do a lot more convincing that there are indeed horrible tragedies going on and that the characters are deeply traumatized by it. Something that that one show a couple seasons back about the suicidal girl beset by monsters that wanted to marinate her or whatever did much more effectively with its disturbing visuals. Everything here is not just off-screen, but only vaguely referenced in dry exposition, not to mention nobody’s much affected by it. They go to a funeral, and are mopey about it… but look at the rack on this lady as she quirkly manhandles this girl for comic relief. The juxtaposition is not intended to be jarring. It’s just a mishmash.
So this starts out weaker, and only gets sillier and fanservicey as it goes, with instead of a monster being a quirky happy-go-lucky supposed murder girl who does no murdering on screen. Nor seems to be mentally damaged at all. She’s just a silly goofball who the protagonist will be… teaching about sex. Yes, the explicitly 14 year old protagonist will be teaching the 10 year old about sex. Excuse me, mana transfer through kissing. This certainly seems like a great idea and not problematic in any way whatsoever.
