Yu-yu Kondo is a 15 year-old third-year middle school student who lives in Kanazawa City, in the country Kaga with “the ability to sympathize with the hearts of others”. Due to his meek personality, though, he finds it hard to reject others and often becomes the unwilling subject of his sisters’ hobbies.
The story begins as Yu-yu, exasperated at his own plight, runs away from home and encounters Megumi Okura. She invites him to the “night amusement park” Wonder Hill to meet her friends.

The amusement park is the gathering place for “Team Blackout”, a group of youths who play Vanguard. And on the night of Yu-yu’s first visit, a serious battle begins to unfold with the team’s flag at stake, with Team Blackout’s leader Danji Momoyama, a skilled fighter with a 19-win streak, taking on a challenge from the mysterious powerhouse fighter, Tohya Ebata.

The intense struggle between the two fighters enthralls Yu-yu, as the cardfight before his very eyes transforms into a scene from the planet Cray itself…
An exciting world of wonders and adventure awaits him, alongside his new friends!