One-Punch Man's latest episode sees Saitama finally get done with the facade of his Super Fights martial arts tournament, just in the nick of time to save the tournament fighters from an all-out assault by the Monster Association. In true One-Punch Man fashion, Saitama's late-game save at Super Fights turned out to be as anti-climatic for the overpowered hero as any other fight he's ever been in - but that didn't mean it was an easy experience for his foes!
Episode 21, "The Ultimate Dilemma" starts off with Super Fights champion (and cocky martial artist) Suiryu still battered and broken by fellow Super Fights competitor Bakuzan. After hearing the Monster Association's master plan for creating human/monster hybrids, Bakuzan submitted himself for the transformation process, and became one of the most fearsome hybrid monsters we've seen. With his transformation, Bakuzan had more than enough power to thrash Suiryu within an inch of his life - but that power didn't mean jack when it came to facing Saitama!
Bakuzan manages to talk a lot of trash to Saitama when the hero finally steps into the Super Fights ring in his full One-Punch Man costume and persona. Bakuzan simply sees Saitama as a puny hero wanting to make a name for himself - that is, until Bakuzan recognizes the bald figure as the same "puny" Super Fights competitor that knocked him out in just one punch. After that the games are done, as Bakuzan attacks Saitama with the full force of his martial arts super-attacks, enhanced with a monster's edge.
Monster-Bakuzan's power is enough to admittedly move Saitama - like, literally, the super kicks and punches the villain hits the hero with are enough to make Saitama slide across the ring a bit. Suiryu thinks that it's Saitama's strategy at work, and the hero is simply taking the punishment as a way of covering the injured martial artists scattered around the ring. However, in truth, Saitama is just trying to work out a dilemma: he cannot remember Bakuzan's name, despite facing him in the Super Fights tournament. Saitama eventually gives up on the memory attempt, and decimates Bakuzan in one punch, leaving the monster's entire upper torso and head completely blown way.
This was definitely Saitama's "coldest kill" in the sense that he utterly destroys Bakuzan as an afterthought. It happens so fast that not even Suiryu or poor Bakuzan himself see it happening as it does; one second the ferocious monster is on the rampage, the next he's mangled corpse littering the arena. It's a quick an decisive end to the monster attack / Super Fights arc, but the victory is a hollow one, as Saitama is ultimately left felling depressed and unfulfilled by his entire Super Fights experience.
One-Punch Man Season 2 is now streaming on Hulu, and on Crunchyroll outside of the United States. The season is directed by Chikara Sakurai (Naruto Shippudenepisode director), for new production studio J.C. Staff. Yoshikazu Iwanami serves as sound director, and Chikashi Kubota contributes new character designs.