Sword of Honor, Blade of Death Quincy M.E. : Season 8 Episode 10

Michael Moroshima, a cop working undercover with the Asian task force and Sam's best friend, is killed while listening in on a deal between the Yakuza and the Mafia. Sam explains to Quincy all about the Yakuza and the Japanese code of honor that means his friend's father will try to find his son's killer and exact revenge. Sam tries to prevent this from happening but finds himself getting into deeper trouble himself.