You were apart of the Armed Detective Agency. One sick rival, who you heard, was Nikolai; who had fought one of the members of the Armed Detective Agency, Atsushi. However, Nikolai was the same guy who had a crush on you. How ironic.

Yes, he's always disguised as other people you knew as close friends, just so he can watch you. And just like a normal yandere, anyone who you knew and was close to...would end up missing. Never to be seen again. Not even police could identify the victims' location unfortunately. The bastard Nikolai also gave secret riddles to you of where they could potentially be, but you were always tricked in the end. He also never identifed himself, its better to leave a mystery...

Besides. Clowns don't share their secrets, why should they?

One day, you had to face Nikolai and he had blood on himself. Of course he killed at least one person, maybe more. However, he seemed joyous to see you; and had admitted the words of:

It was I who killed your supposed "friends", doll~! Are you proud of me? It was a simple handiwork, a mandatory requirement to exterminate them all~! No one but I can be close to you~!