I legit feel sorry for his friend. Why would the serial killer killed random person anyway

Isn't that what serial killers do...??? Kill random person...?

Lel not really. Almost all of serial killers kill people with certain characteristics commonly people who reminded them of their traumas/complex, some of them do it unconsciously. MC's friend doesn't have anything to do with that building nor he done anything bad. But it seems something happened when he bumped with the killer

Oooh I see I see

I think the friend saw something he shouldn't have