Yuugi Mutou, a high school student enduring bullying during the day, finds solace in board games and puzzles by night, inspired by his grandfather and their shared home in a game shop. After unlocking the Millennium Puzzle's secrets, Yuugi unlocks a darker side – Yami Yuugi – who emerges when Yuugi faces extreme challenges. Reluctantly transforming into a bold and risky vigilante, Yuugi challenges wrongdoers to life-threatening games. Despite his struggles, Yuugi forms unbreakable bonds with former bullies turned allies. As they face more sinister foes utilizing games for malevolent ends, Yuugi and his friends must confront threats endangering their very existence.