[MXF] Looking to do the Boy X monster (or girl x monster) trope for a long term, romance and and story based rp!

Good evening! I'm Realm, a male roleplayer with some years of experience. I'm typically active every day except for Tuesdays, and I'm looking for something rather specific vibes wise, so bear with me! Basically, I'm looking for something along the lines of stranger things, Studio Ghibli movies like Ponyo, and similar style media where a character comes in contact with a supernatural character either fleeing from the government, other supernatural, or a similar faction. I'd like ageplay to be involved here, so please don't apply if that's not your cup of tea. For me, supernaturals can be monsters, but also things like witches, espers, failed experiments, and more, as long as it's something the government or a faction would be highly invested in studying!

As for what the creature is, I'm leaving it up to me and my partner, as well as who plays what. I'd prefer to be able to explore things like what counts as being a person, some more intense things things like combat (for when running isn't an option) and how the characters approach that (lethally, non lethally, a mix?), as well as the monster learning how to better emulate and blend in with society. If that sounds like a fun idea, please do dm me! I have a few example images posted below!Art examples
https://www.pixiv.net/en/artworks/84618036
https://www.pixiv.net/en/artworks/91728791
https://www.pixiv.net/en/artworks/93094943
https://www.pixiv.net/en/artworks/73949136