Sly C. - Kokitsune's Brother

Yep, he's her brother.

Name: Akame. (Guess what it means)
Surname: Seirei.
Birthday: 6th April 1970
Species: Lynx
Age: 32 years old.
Nationality: Japanese, raised in Germany.
Dubber: Eiji Takemoto (Japanese) / Jerry Orbach or Jonathan Freeman (English)
Personality: Very protective towards his "one-year-younger" sister Kokitsune. He often does not approve her decisions, but he always respect her, making her notice her mistakes.
Character: Akame was, with Kokitsune, the only survivor of the massacre of their family by a rival Yakuza family (Japanese mafia) ten years ago. He was always convinced that the sister didn't joined Yakuza by her will, but was forced to. After his sister was imprisoned, without any reason to remain in Germany, Akame returned to Japan. Then, he decided to train himself with karate in a monastery with monks.

When he was ten years old, when he was playing with Kokitsune and her Chemistry Kit, she had the "accident". Akame had it too, being with her, but less than her, so he turns into a dragon more rarely than the sister.
(His dragon form, in the picture, is much bigger than the sister's one)

In Sly 3, he comes back to watch over Kokitsune. He doesn't approve her relationship with Dimitri, but he enjoys the fact to be an uncle and he loves his nephews. His first meeting with the Cooper Gang was quite nice, and he was really impressed by Panda King.

Akame and Kokitsune (c) me
Sly Cooper (c) SuckerPunch