The Adventure of Denchu-Kozo

Hikari is a boy who is bullied and teased by the other boys at school because he has the odd distinction of having an electricity pole growing out of his back. However, one of his classmates, a girl named Momo, comes to his rescue. Hikari thanks her by sharing his secret possession with her: a time machine. He then activates the time machine which transports him 25 years into a dark, dystopian, world of the future. There he encounters members of the Shinsengumi Vampire Gang in the process of hunting a woman named Dr. Sariba who is revealed to be Momo's future self. She explains to Hikari that she had been long expecting his arrival from the past and that he has a crucial role to play here -- he and he alone must save the world.