Responses
Um i dont know if its this one, but i thought it fit with the details you said. It doesnt happen in the first chapter with friends tho, but it is the seme who has the forehead scar
https://www.mangago.zone/read-manga/scratch_blue/
I need to find this manga.
So I remember seme and uke are friends and in first ch , they were with other friends in a room and seme laying down and a little scar showed on his forehead, uke was looking and he felt sad and apologized to seme ,seme said it's okay cause the scar is from long ago .