Menma is a being that should not exist- a living paradox. After Obito (in the disguise of Tobi) used Limited Tsukuyomi, his power touched upon an alternate reality. This other world paralleled the original ninja world, even down to its history and people, but with key differences. Unlike his counterpart, the Naruto of this dimension succumbed to the hatred and evil desires within him. Menma subsequently murdered and kidnapped other shinobi purely out of a desire to end their meaningless existences, and to enhance his own power.