Tantei wa Mou, Shindeiru.

Thwarting a hijacking with the beautiful, silver-haired detective, Siesta, transforms Kimihiko’s young life. Their success kicks off years of crime-solving and confronting syndicates around the world, until Siesta dies. Left with questions, Kimihiko moves on. But now, a new case may open healed wounds as it connects to an assassin, a world conspiracy, and his dead partner!

(Source: Funimation)