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, the season follows Monkey D. Luffy's adventures with his Straw Hat Pirates crew. The season adapts material from the "Egghead" story arc, from the rest of the 105th volume to the beginning of the 111th volume of the manga series One Piece by Eiichiro Oda. It deals with the Straw Hat Pirates meeting Dr. Vegapunk on the futuristic-looking island, Egghead, which leads into an event that shocks 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 "Fish-Man 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.

Six 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. From episode 1123 to episode 1138, the opening theme song is "Angel & Devil" (天使と悪魔, Tenshi to Akuma), performed by Gre4n Boyz, which is also used as the special ending theme in episode 1137, while the ending theme song is "The 1", performed by Muque. From episode 1139 onwards, the opening theme song is "Carmine" (カーマイン), performed by Ellegarden, while the ending theme song is "Punks", performed by Chameleon Lime Whoopie Pie.