One Piece season 21

The twenty-first season of the One Piece anime television series is produced by Toei Animation, directed by Tatsuya Nagamine (until episode 1122), Wataru Matsumi (beginning with episode 1123), Satoshi Itō and Yasunori Koyama. The season began broadcasting on Fuji Television on January 7, 2024. Like the rest of the series, this season follows the Emperor Monkey D. Luffy's adventures with his Straw Hat Pirates. The season adapts material from the "Egghead" arc, from the rest of the 105th volume onwards of the manga series of the same name by Eiichiro Oda. It deals with the Straw Hat Pirates meeting Dr. Vegapunk on the futuristic-looking island, Egghead, which will lead into an event that will shock the world.

In October 2024, it was announced that the anime series would go on hiatus until April 2025, and that a remastered and re-edited version of the "Fishman Island" story arc would air in the show's timeslot during the break. After returning, the show would move to Sunday nights for the first time since 2006, marking the anime's return to a primetime network timeslot. Episode 1123 premiered on April 5, 2025, as part of the network's Premium Saturday timeslot before moving to its fixed Sunday night slot a day later, beginning with episode 1124 on April 6.

Four pieces of theme music are used for the season thus far. From episode 1089 to 1122, the opening theme song is "Uuuuus!" (あーーっす！, Āssu!; a drawn-out spelling of 'Us!') performed by Hiroshi Kitadani, while the ending theme song is "Dear Sunrise" performed by Maki Otsuki. For episode 1123 onwards, the opening theme song is "Angel & Devil" (天使と悪魔, Tenshi to Akuma) performed by Gre4n Boyz, while the ending theme song is "The 1" performed by Muque.