Yu Yu Hakusho

Death of a Spirit Detective (3x23)

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Yusuke comes to terms with the fact that he cannot defeat Sensui. Watching but unable to help, Kuwabara fights off emotion with rage as he remembers all the good times and bad he's had with his best friend. Kuwabara manages to free Kurama and Hiei, but it's too late. Yusuke Urameshi has been destroyed.