The Friendship Cup enters its second round with Yuzu chosen to duel Sergey. With the field still destroyed from Shun's duel with Dennis, all subsequent matches will take place in the dueling lanes around the arena outside. Yuzu takes the first move and prepares her strategy, and Sergey responds by summoning a monster in attack position with 0 ATK. While the spectators are confused, Yuzu summons more monsters and goes on the offensive, but Sergey uses his monsters, Thorn Prisoners, to defend himself by paying Life Points. He performs a Synchro Summon, intending to damage Yuzu's Life Points with a combo, but Yuzu fuses her three monsters into "Bloom Prima the Melodious Choir." Sergey's combo backfires and he takes more damage as a result. Every time he loses life points, holographic thorns manifest around Sergey to inflict pain on him. Yuzu fears for his safety, but Sergey finds pleasure in the pain and keeps dueling.
Yuzu destroys Sergey's Synchro Monster, but he revives it along with its Synchro Materials. However, Yuzu's repeated attacks and his own cards have caused Sergey's life points to drop to a scant 200. Yuzu calls for the duel to end for Sergey's safety, and protests the conditions of the City, forcing Sergey to duel like this and then sending him to do labor in the underground facility. However, Sergey interrupts her; he enjoys crushing his opponents when they think they've won, and finds it beautiful. He goes berserk and tells her Damon was no fun like her, and he'll enjoy finishing the duel with her in this state. He activates Polymerization and fuses his three monsters into "Thorn Over Server - Van Darli Zuma" with 0 ATK. By its effect, its ATK increases by Sergey's life points subtracted from 2500, and then doubled. With an ATK over 4000, Sergey uses his monster's effect to sap the ATK of Bloom Prima to 100, and attacks.
Yuzu sees an Action Card and moves to grab it, but Sergey spins his D-Wheel around and rams her, sending her flying through the air before she can reach it. The attack connects and Yuzu is defeated in an instant, and she crashes through a building. Yuya watches the television in horror as Melissa reports they're unable to see what happened due to the smoke from the explosion, and he cries out for Yuzu.
This episode provides example of:
- Big Eater: Yugo. His first shot in the episode shows him having eaten 3 bowls of food. By the last time he's shown, he's made his way through many, many more bowls.
- Combat Sadomasochist: Sergey, Sergey, Sergey. He's shown sweating bullets from the pain of the damage he takes, but enjoys it just a little too much. He also calls it beautiful when Yuzu thinks she has won and he knows he can utterly destroy her.
- Foregone Conclusion: Summaries for Episodes 78 & 79 imply that Sora gives Yuya a message about Yuzu being saved from death in the aftermath of her duel against Sergey, to the latter's relief.
- Hope Spot: Yuzu is easily winning the duel, and as she calls out that the Friendship Cup and City's lifestyle is wrong, it seems the crowd is finally taking notice and she's getting through to them. Then Sergey interrupts her...
- Madness Mantra: Sergey begins repeating "endured" over and over and over, as he breaks his limiter and prepares to make his game-ending move.
- Mood Whiplash:
- The majority of the episode is fairly lighthearted, with Yuya, Yugo, and Serena cheering on Yuzu. Then, Sergey's mocking Yuzu for thinking that she's won, and she gets thrown into a building shortly thereafter. Downplayed using the interspersed moments of Sergey's Nightmare Faces.
- The last shot is of Yuya screaming Yuzu's name because she's very obviously been badly hurt. Then we get the upbeat and hopeful ED.
- Nightmare Face: Sergey makes these all the way through the duel.
- Pragmatic Villainy: Roget is angry with how brutal Sergey was with Yuzu, since he wants her intact to aid in his plans, and immediately sends Security to retrieve her after the duel.
- Reality Ensues: The Arc Villain sends a Psycho for Hire to fight and subdue an important target? The Psycho almost kills her because he's so violent and overzealous. Roget is clearly not happy with this.
- Red Eyes, Take Warning: When Sergey Fusion summons, both his eyes are shown glowing red. It's shortly followed by Sergey dealing 4700 damage and blocking Yuzu from getting an Action Card, resulting in Yuzu going flying through a window.
- Say My Name: Yuya screams Yuzu's name at the end of the episode after she is thrown through a window.
- Theme Music Power-Up: Sergey gets a rock tune going as he summons his ace monster.
- Weak, but Skilled: All of Sergey's monsters have 0 ATK and DEF as their base stats, but have effects that help Sergey slowly lower his life points in a controlled manner, which is necessary for the ATK calculation of his ace.
- Wham Episode: And one of the darkest to boot, with Yuzu getting thrown off the track and Sergey proving to be the most deranged manic villain of the series so far.
- Wham Shot: Sergey Fusions Summons out of nowhere. Downplayed since we know Jean-Michel Roget was previously affiliated with Academia.