Yugi challenges the deep-sea duelist Mako Tsunami, who's friendly enough to share fish with the group before dueling. Mako's strategy revolves around using the sea to hide his monsters, powering them up and letting them strike Yugi unawares. When Yugi tries to use Mystical Moon to power up Silver Fang, a wolf, he finds it has the unexpected side effect of making the tide come in, further submerging and powering up Mako's monsters!
All Yugi has left is a small island of land, and with Mako's Fiend Kraken on the field things don't look good at all. Yugi decides to use Giant Soldier of Stone to attack and destroy his own spell card. With the moon gone, the tide recedes, and Mako's fish monsters are filleted. Mako accepts his loss and hands over his Star Chips, revealing that his dream was to win enough money to buy a fishing boat.
This episode contains examples of:
- Failed Attempt at Drama: When Mako first attempts to introduce himself, a dramatic wave appears behind him — and crashes over him, dragging him back into the sea. He tries again, only for an octopus on his head to ruin things again.
- Making a Splash: Mako's monsters, as well as his dueling field.
- New Rules as the Plot Demands: "Attack the moon"? Okay, since when can a Normal Monster attack and destroy a Spell Card?
- Nice Guy: Mako's one of the most honorable enemy duelists in the series. He and Yugi regard each other as Worthy Opponents.
- Tastes Like Friendship: Mako shares his fish with Yugi and his friends.