any original plots? I read too much isekai they're getting boring (;O;)

Genwaku no Kodou
Terrarium Adventure
Master Drifting Away Again
Dam of the Forest
1/2 Prince

https://www.mangago.zone/read-manga/please_throw_me_away/
https://www.mangago.zone/read-manga/adeline_s_twilight/
They have regressed fl but no isekai - the plot and (secret) world building are original.

And maybe this but only if you can take a fl who starts out weak but grows
https://www.mangago.zone/read-manga/the_admiral_s_monster_wife/