Grand Blue Dreaming Season 4 Confirmed the Same Day Season 3's Finale Aired
Grand Blue Dreaming isn't making its fans wait long between rounds of diving, drinking, and general chaos at Izu's fictional dive shop. According to the anime's official website, a fourth season was confirmed on September 21, 2026 (JST) — landing just a day after the third season's 12th and final episode aired in Japan. For a comedy that's spent three seasons proving its staying power, that's about as clean a handoff from one season to the next as a franchise can manage.
Here's a full rundown of what's confirmed about Season 4, along with where Season 3 left things and everything worth knowing about the show for anyone catching up.
The announcement, confirmed
Grand Blue Dreaming's official anime website posted the Season 4 news on September 21, immediately following the airing of Season 3's finale the day before. The confirmation arrived as a teaser announcement — a text reveal accompanied by a teaser visual — rather than a full trailer. No release date, premiere window, or episode count has been attached to it yet. It's the kind of announcement studios tend to lead with when a project is locked in but the logistics still need to be worked out: confirm the thing is happening first, follow up with scheduling details later.
Still, the timing here is notable on its own. Going from a season finale straight into a next-season confirmation within roughly 24 hours signals that whatever production committee is behind Grand Blue Dreaming had this planned well in advance, rather than waiting to gauge fan reaction before greenlighting more episodes.
Season 3 closes out its Palau arc
Season 3 wrapped its 12-episode run with a finale that closed out the season's central setting: Palau, which marked the first time Grand Blue Dreaming's anime has taken its cast outside Japan. That's a meaningful shift for a series that's spent its previous two seasons rooted entirely around the Izu dive shop and its surrounding coastal town, and it gave Season 3 a different backdrop to build its comedy and diving sequences around for the length of the season.
Beyond confirming that the finale capped off the Palau setting, there isn't detailed, verifiable reporting available yet on the specific events of episode 12 itself. Rather than guess at scene-by-scene finale details that haven't been reliably sourced, it's worth leaving that part open for anyone catching up — the safest summary is simply that Season 3's Palau arc reached its conclusion with the season's last episode.
Season 3, by the numbers
For anyone who missed it, Season 3 premiered July 6-7, 2026, produced jointly by Zero-G and Saber Works, with Shinji Takamatsu returning to direct. Takamatsu has been attached to the franchise since its earlier seasons, so his continued presence gave Season 3 a consistent directorial hand even as the setting shifted to Palau for the first time.
The season ran its full 12-episode course from that July premiere through the finale that aired the day before the Season 4 announcement — a fairly standard single-cour run for the franchise, matching the pacing of its earlier seasons.
The returning cast
Season 3 brought back the show's established main cast in full. Yuma Uchida reprised Iori Kitahara, the series' central protagonist, alongside Chika Anzai as Chisa Kotegawa and Maaya Uchida as Nanaka Kotegawa. Ryohei Kimura returned as Kohei Imamura and Hiroki Yasumoto as Shinji Tokita — the two upperclassmen whose influence over Iori has defined much of the show's comedic engine since Season 1.
Rounding out the cast, Katsuyuki Konishi reprised Ryujiro Kotobuki, Toa Yukinari returned as Azusa Hamaoka, Kana Asumi as Aina Yoshiwara, and Aya Yamane as Sakurako Busujima. That's the full established ensemble carrying over intact, which tracks with how consistently the franchise has kept its cast together across seasons rather than making changes along the way.
No casting announcement for Season 4 has been made yet. The September 21 confirmation covered only the fact that a fourth season is happening, without extending to a statement on which cast members are returning. Given how tightly the Season 4 announcement followed Season 3's finale, and how consistently this franchise has kept its voice cast together season over season, there's little reason to expect changes — but it hasn't been formally confirmed for Season 4 specifically.
The theme songs
Season 3 opened with "Natsuko," performed by Funky Monkey Babys, and closed each episode with "Hadaka no Mermaid" by Mameshiba no Taigun. Both tracks were tied specifically to Season 3's run; nothing has been said yet about theme songs for Season 4, which is unsurprising given how early-stage the announcement still is.
What Grand Blue Dreaming is about, for newcomers
For anyone unfamiliar with the series, Grand Blue Dreaming follows Iori Kitahara, a college freshman who moves in with his uncle's family to attend a university near the coast, expecting a quiet start to his new life. Instead, he gets pulled into the orbit of Grand Blue, his uncle's diving shop, and the loud, perpetually drunk crowd of upperclassmen and diving club members who treat the shop as their unofficial hangout. What follows is less a diving anime in the traditional sense and more a slapstick comedy about a group of college students who happen to be enrolled in a diving club, built around drinking, stripping, screaming matches, and the occasional genuine moment of underwater beauty once the show remembers it's ostensibly about scuba diving.
That contrast — laid-back diving scenery undercut by absolute chaos on land — has been the show's defining comedic rhythm since it debuted, and Season 3's shift to a Palau setting gave that same formula a new environment to play out in, with the cast's dynamic staying intact even as the backdrop changed.
The manga behind the anime
Grand Blue Dreaming is based on the manga by Kenji Inoue, who writes the story, and Kimitake Yoshioka, who handles the art. The manga has been serialized in Kodansha's Good! Afternoon since April 2014, and has been collected into 24 volumes in Japan as of the most recent count. That's over a decade of ongoing serialization, giving the anime a deep well of material to keep adapting from as it moves into a fourth season — there's no shortage of source material standing between where the anime currently is and where the manga has continued to run.
What's still unknown about Season 4
It's worth being precise about what has and hasn't been confirmed here. What's locked in: a fourth season is happening, and a teaser visual has been revealed alongside the text announcement. What hasn't been announced: a premiere date, a release window, an episode count, returning cast, staff details, or any indication of where in the manga Season 4 will pick up. Anyone encountering more specific claims about Season 4 circulating online right now — a release month, a confirmed setting, or a cast list — should treat those as unverified until the official Grand Blue Dreaming website or a major outlet puts out something more concrete.
That's a normal place for a same-day renewal announcement to sit. Confirmation tends to come first, with the scheduling and staffing details following once those pieces are actually locked into place.
Bottom line
Grand Blue Dreaming closed out Season 3's 12-episode, Palau-set run and got a Season 4 confirmation within about a day of the finale airing — a turnaround that suggests real confidence from the production committee behind Zero-G and Saber Works' work on the series. Shinji Takamatsu's continued direction and the full returning cast from Season 3 give the franchise a strong baseline heading into whatever comes next, even with a premiere date, staff details, and casting for Season 4 all still unconfirmed. For now, the headline is simple: Iori Kitahara and the rest of the Grand Blue crew are coming back for more, even if nobody knows yet when or where that'll happen.
No release window has been set for Season 4 yet; expect a cast and staff rollout, plus an eventual premiere date, to follow the teaser visual in the coming months.