The city where network systems are developed: Den City. The giant company SOL Technology Co. is based there, and it uses advanced technology that it created to construct "LINK VRAINS," a virtual-reality space. In LINK VRAINS, a mysterious hacking group that hacks through duels called "The Hanoi Knights" appears. Their goal is to bring about the destruction of the "World of AI: Cyverse" that exists somewhere in the network. However, there is one duelist in LINK VRAINS willing to stand up to this threat. His name is Playmaker. Playmaker defeats The Hanoi Knights in a fierce duel, and then leaves without saying a word. Playmaker's real identity is the high school student Yūsaku Fujiki. For Yūsaku, he spends so much time in LINK VRAINS because he is searching for the truth to an incident that happened in his past.