the way everyone was shitting on Yamadera-kun a few days ago saying they didn't care about him and now y'all are shedding tears for him.
I think he's a great addition to the story bc as we've seen in the first chapter, sayo would have never become comfortable with himself and would never have evolved as a vampire nor met his vamp friends. Basically without Yamadera-kun he would've still be stuck in fear and loneliness