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.