Aoi Yūki Returns to a Role She Already Owns
Sirotan isn't a manga or light novel adaptation. The character is a harp seal mascot created in 1999 by Creative Yoko, a Nagano-based company whose core business is soft, huggable plush toys, and it has been a fixture of Japanese character shops for 27 years. The TV anime, announced back in March, is the property's first weekly broadcast series.
Aoi Yūki (Tsuyu Asui in My Hero Academia, Tanya Degurechaff in Saga of Tanya the Evil) voices the title seal, a role she had already played in short animations on the character's official YouTube channel before the TV series was greenlit. She heads a four-character main cast: Miyu Hanasaki (花咲心優) plays the otter-dog hybrid Rakkoinu, Rina Hidaka (Silica in Sword Art Online) plays Sheru, and Riyo Iwai (岩井里世) plays Ramune.
On the production side, Arisa Okada directs at animation studio Lesprit, with Sei Yoshitsuki handling series composition and scripts. TV Asahi and Shin-Ei Animation are credited with planning and production, and the show airs as part of PicoAni, the new short-anime programming block TV Asahi announced earlier this year.
A Hot-Air Balloon Send-Off and Cast-Signed Message Boards
The new main visual, unveiled September 1 in a PR TIMES release, shows Sirotan and friends floating off together in a hot-air balloon. Poster versions are going up at the pop-up shop currently running at Yokohama Porta (directly connected to Yokohama Station) and at directly operated Sirotan stores across Japan.
The more interesting piece is the countdown campaign. From September 4 through late November, four Sirotan stores in the greater Tokyo area will each display a commemorative message board featuring an autograph board with a handwritten message from one cast member, matched to their character. The Harajuku Takeshita Street store gets Sirotan and Aoi Yūki, the Ikebukuro Sunshine 60 Street store gets Rakkoinu and Miyu Hanasaki, the Yokohama World Porters store gets Sheru and Rina Hidaka, and the Sirotan Friends Museum at LaLaport Tachikawa Tachihi gets Ramune and Riyo Iwai.
Fans who visit can write a support message on a sticky note and add it to the board, and Creative Yoko says the growing boards will be shared on the official Sirotan social media accounts. It's a fittingly analog promotion for a franchise built on physical plush.
A line of TV anime original merchandise, including plush toys and mascots themed around the show's look, follows on September 11 at Sirotan stores nationwide and the official online store.
Looking Ahead
The broadcast starts Saturday, October 3, 2026 at 4:29 p.m. on TV Asahi. Notably for overseas fans, the release states that every episode will also be streamed on the anime's official YouTube channel, though it doesn't say whether those uploads will be viewable outside Japan. No international streaming partner has been announced.
The message boards stay up through the end of November, running well past the premiere, so the campaign doubles as a launch-window event. If you're in Tokyo or Yokohama this fall, a sticky note at a plush shop is about as low-stakes as anime fandom participation gets.