Episode 4 of Bet begins with Yumeko, portrayed by Miku Martineau, teetering on the edge of darkness. As she holds a weapon to Raymond, the man connected to her parents’ death, she’s ready to end his life—but ultimately pulls herself back. The emotional confrontation leaves her rattled, and she becomes so consumed by thoughts of vengeance that she accidentally constructs a prototype bomb in the library, which Michael eventually stumbles upon.

Amid this tension, a bizarre and wildly inappropriate side bet begins to spread across the school: a wager on whether Ryan is still a virgin. The bet takes the campus by storm, with students shamelessly propositioning him in hopes of a quick cash-out. Kira suspects this chaos is no accident, theorizing that the bet was deliberately designed to distract and destabilize. She discusses her concerns with her sister Riri, who has just received a mysterious letter from their father.

A Deadly Plot and a Risky Confession

In the library, Yumeko opens up to Michael about her traumatic past. She recalls how she witnessed her parents’ car explode right in front of her eyes, shortly after they’d been seen arguing with a man—Raymond. She then confesses that she’s working on an explosive and enlists Michael’s help to perfect it.

Meanwhile, Mary returns to the gambling scene with a scheme of her own. After obtaining a loan, she bets that Ryan has already lost his virginity. Her plan? Pretend she and Ryan had slept together, allowing him to save face and letting her walk away with the winnings. But Ryan refuses. He’s in love with Yumeko and won’t fake something so personal.

The Recital, the Bomb, and the Betrayal

As the day of the school recital arrives, tensions rise. Blake is scheduled to perform, and her stepfather, Raymond, makes a rare appearance. Overcome with anxiety, Blake nearly sends him away. But Yumeko encourages her to go through with the performance, reminding her that Michael had promised her safety—on the condition that only Raymond would be in danger.

Later, Mary urges Yumeko to take the virginity bet into her own hands by sleeping with Ryan. Yumeko visits him that night, but Ryan, realizing she doesn’t return his feelings, chooses not to go through with it.

Inside the packed auditorium, Raymond takes a seat—precisely the one Yumeko has rigged with an explosive device. But just as her revenge seems imminent, Yumeko realizes she’s been deceived: Michael has tampered with the plan, and the bomb doesn’t detonate.

A Shocking Twist: The Real Mastermind Revealed

After the failed assassination, Kira confesses something stunning to Yumeko—she was the mastermind behind the virginity bet all along. Her goal was to destabilize the council further and shake them out of their growing complacency.

In a panic, Yumeko chases after Raymond, only to arrive too late. She watches, breathless, as Raymond gets into a car with Blake. Moments later, the vehicle explodes in a fireball down the road. But rather than react in horror, Yumeko smiles—believing justice has finally been served.

Yet, the real twist comes in the final shot. Riri stands alone by a window, holding her father’s letter. It was she who planted the bomb and triggered it—silently claiming vengeance for reasons not yet revealed.