Orihara Izaya♂

Izaya is a young man who sells information for his own satisfaction and is behind the most relevant events in the series making him the principal antagonist of the series. He claims to love the entire human race, except for his arch-rival Shizuo Heiwajima, and exhibits said love by putting humans in often miserable conditions and observing their reactions. He is a master of parkour, and is also quite skilled with his flick-blade, as he is implied to be the only one capable of leaving numerous cuts in Shizuo's bartender suit after a fight. Online, he pretends to be female, and talks in a feminine manner in the chatroom. Izaya also has two younger sisters, Mairu and Kururi.

[from Wikipedia]