Durarara!! Re;Dollars Arc, Vol. 1 (manga)

Mikado Ryuugamine is just trying to pass his second year of high school peacefully, but that plan is out the window when he gets word that someone within the Dollars gang is causing trouble. Everybody has issues: Izaya is scheming, Mikado's classmate knows his secret, and Shizuo's being targeted by a mysterious girl...just another day in Ikebukuro!