"A Past to Be Erased," episode 215 of the original "Naruto" anime, follows Naruto, Menma, Neji and Tenten as they seek to protect a town ravaged by bandit attacks. During battle, Menma is injured, and it is revealed that he was a former member of the bandits' gang.
The ninjas know that it is only a matter of time before the bandits return to attack the town once again. Eventually they do, and Menma is injured in battle. Naruto and the rest of the party then discover that not only is Menma a former bandit, but he was also present when the bandits attacked the town previously. Menma apparently has no memory of this.
Menma's change of heart allows him to divulge the plan of the bandits to flood the town with water from a dam. After revealing that he did not lose his memory and acted willingly in the raid, Menma sacrifices his own life in a final act of heroism. He causes a rockslide that stops the water and saves the town but gets crushed in the process. Naruto eventually defeats the leader of the bandits in battle. He mourns Menma's death at the end of the episode.