For the Sake of Justice?! The Man Who Deserted the Shinigami
Komamura performs his Bankai, Kokujo Tengen Myo-oh, to subdue Tosen. However, Tosen has already deduced the weakness of Komamura’s Bankai from years of working closely together. Despite the damage received, Komamura refuses to give up on his former friend, throwing out the question of why Tosen chose to become a Soul Reaper in the first place.
Aired 28/09/2010EP 290 - For the Sake of Justice?! The Man Who Deserted the Shinigami

Bleach
Ichigo Kurosaki is a rather normal high school student apart from the fact he has the ability to see ghosts. This ability never impacted his life in a major way until the day he encounters the Shinigami Kuchiki Rukia, who saves him and his family's lives from a Hollow, a corrupt spirit that devours human souls.
Wounded during the fight against the Hollow, Rukia chooses the only option available to defeat the monster and passes her Shinigami powers to Ichigo. Now forced to act as a substitute until Rukia recovers, Ichigo hunts down the Hollows that plague his town.