u reminded me of a manga(i'm not sure if it was manhua or manhwa), i've read it a really long time ago on wattpad, the mc had a red hair and he was so narissastic and loves his looks so he had like a routine to stare at himself in the mirror everyday before school(or university? not sure) and kiss his mouth in the mirror, and one day while he was kissing himself he felt smth wet and when he opened his eyes the He in the mirror was kissing him back and got of the mirror to make out with him it was interesting, i remember that later the "him" who got out of the mirror started growing taller than him and change. i REALLY wanna remember its name but i never did nor i found it when i searched up the story
im curious as hell cuz i jus found out ive never seen one