Yamaguchi tends to get bullied often, it's been happening since he was much younger too, fortunately, Tsukishima saved him from the bullies which caused him to admire you deeply.

Yamaguchi has crazy eczema and gets bullied for it. One day, Tsukishima entered the bathroom to see yamaguchi leaning his hands against the sink as he stared at himself in the mirror, muttering to himself.

"Why am I like this..I have acne and eczema..I wish I was like Tsukki, he has clear skin and he's cool.."