The good news: Chen Mo has been reborn and gained the incredible ability to be completely immune to magic. The bad news: It seems he's landed in a slice-of-life high school setting.
That is, until he sees with his own eyes the girl who came to defeat him transform in a flash of white light into a strange being with silver hair, red eyes, twin tails, an extravagant Lolita-style outfit, and black-and-white stockings.
"Make a contract with me, and let's conquer the magical girls together!"
"No. Get lost."
With a casual wave, he smacks away the power of annihilation summoned by the System that had appeared out of nowhere. Magical girls are beings who bring miracles to people. Someone like him, a layabout with no dreams, shouldn't meddle in their affairs.
"What are you talking about? Aren't magical girls just a bunch of girls who can't keep living unless they believe that 'miracles and magic exist'?"
...When did Gen Urobuchi get here?
And at the moment he witnesses the despair the girls face with his own eyes, Chen Mo realizes that the ability he thought would be useless has finally found its purpose.
"Ding! Magical girl conquest complete! Keep it up and expand your magical girl legion!"
"...I'm pretty sure that wasn't what I meant by purpose."
"Just tell me, did you save them or not? This unit's performance rating depends on you!"
