tryna remember this webtoon i read years ago help

i honestly forgot the whole plot but its like a school life romance webtoon and the mc is this neeky lad with greyish hair (with glasses??) and a popular girl with dark brown hair with bangs. the title was like hello! merry! or sum like that. im pretty sure it got ghosts n possessed people

all i can remember is this one scene where the boy is infront of a mirror and his reflection isnt matching up and he gets possessed or sum freaky ass shi