Yu-yu's real problem isn't the card game, it's that he can't say no to anyone, and the game becomes the place where he finally gets to make a choice that's actually his. Wonder Hill exists in that perfect pocket of time where misfits become something like a family, and Vanguard is just the language they use to talk to each other. By the time you realize this show is about a kid learning to have a spine, you're already invested in whether he wins the next match.

Fifteen-year-old Yu-yu, a third-year junior high student in Kanazawa, can sense what other people feel but cannot bring himself to turn down a request. When his sisters' demands finally become too much, he runs away from home. Megumi Okura comes to his rescue and brings him to Wonder Hill, an amusement park that opens at night, where her friends in Team Blackout meet every evening to play the card game Vanguard. That night, a serious fight for the team's flag is set to take place between Blackout's leader, Danji Momoyama, and Tohya Ebata, a mysterious and powerful fighter. As Yu-yu watches, their match turns into a world of vivid images. Pulled in by the game's allure, he begins to connect with Megumi, Zakusa Ishigame, Tomari Seto and Danji, and discovers a new world alongside his new friends in this action adventure.