It's not as bad as it sounds really
I think I read a fanfic for something that a male character got a vagina for a few days for magic cursed reasons and he get his period and his boyfriend is like "I've heard orgasms help with cramps" they put some towels in the bed they fuck and later take a shower together dude even gets him chocolate
And I'm in my period rn and I wish it was me, gods I wish
Don't ask me anything, i don't have smut that they did it when she's on her period but i do have manga that about period kink maybe
https://www.mangago.zone/read-manga/aiko_no_ma_chan/

Please don't kink shame me a lot about this
But any straight smut out there where the girl is on her period
Manga or hwa