Kuro is a 18 year old depressed girl who is obsessed with video games. She is rank number 'zero' in all the games she plays. Her username is always filled in as a simple word: Ace. People say she's unbeatable and can even beat the mysterious [ ], or blank. What they don't know is that she is friends with the mysterious duo behind blank, and one day when she comes over, she gets put in a new world.

[This happens after Sora and Shiro defeat Tet and become god. (even though that didn't happen in the light novel or anime since the story's still going but just go with it)