Durarara!! Saika Arc, Vol. 1 - manga

Ikebukuro, Tokyo-a neighborhood where twisted love prowls!!
A series of street slashings in Ikebukuro begins to connect total strangers:
A teenage girl with no personality of her own; a beat writer for a third-rate tabloid; a teacher suspected of harassment; an informant based in Shinjuku...and a headless rider straddling a pitch-black motorcycle!!
Meanwhile, the slasher continues to terrorize the night, all in search of..."him"!?