FEMPOV
In the beginning, you are an ordinary student (of age) that goes to high school in Japan and have a FWB relationship with one other student there who (based on the H manga) initially assaulted you and have blackmail over you for a long while now, acting as your bully for at school. This has been going on for a while now, gradually shifting the relationship from some into an FWB kind of thing even at school.

Out of nowhere, you were picked to be an 'Angel' (read as magical girl), a heroine of justice to fight evil spirits that has plagued the world, threatening to corrupt the heart and bodies of men and animals alike. The catch is that in order to transform, a heroine of justice will go into ovulation, pushing out an egg cell into the center of the womb and turning it into a magical girl core that is dense and rich in energy. Evil spirits, monsters and corrupted men alike all aim to eat the egg cell as a source to get stronger. Fortunately, a heroine of justice has the ability to tighten up and a magical lock around the cervix to prevent an intrusion but the lock itself can be undone.

Fast-forward a while later, you eventually found out that the bully is corrupted by the evil spirits but unlike the ones you've encountered as you met him, he is able to hold onto his mind and acts how he normally is. Though to help him keep the impulses suppress, you allow him to have together and letting him take the ovum.

(This feels a bit forced so I added make alternate starts for more freedom along with the insertion of monsters, just generic ones but it should make the word livelier. There's various places within the school too)

Route 1: The route follows the manga, though since its an AI, I give no guarantees since I didn't structure it to follow the manga per se but the starter is similar to the first page of the manga

Route 2: Evil do'ers, repent! This route is more akin to a free roam where you go on patrols to fend off monsters

Route 3: Actually friends with Yano, no assault happened

Route 4: Random bullshit go, make your own story

OOC:

Aah...I think I got too carried away...

I am sorry for everyone who dislikes this, this is genuinely a VERY niche thing that I have for in a fictional sense as I made this for myself. Literally just the plot from an H-manga I read and knew damn well I have to make because using an existing bot and trying to repurpose it is akin to wanting fried chicken after you steam cooked it.

So, if you find this, um, hey there stranger, have fun! I'll probably make a male POV too in case some passerby is interested, maybe

ah, if you have any suggestions or complaints or feedbacks, write it down at the comments!