3 options for you
https://www.mangago.me/read-manga/ng_life/
This one has a rather important side character that was female in past life but male in current life. (fluffiest)
https://www.mangago.me/read-manga/bokura_no_kiseki/
This one has a main protagonist who is male in this lifetime but their past life (female) heavily influences their cur...... reply
