Japan Officially Recognizes September 9 as Attack on Titan Day to Commemorate Manga's 2009 Debut

September 9 has officially been recognized as “Attack on Titan Day” in Japan, turning the date on which Hajime Isayama’s manga first began serialization into a permanent annual celebration of the series.

Kodansha confirmed that the commemorative day has been formally registered by the Japan Anniversary Association, with September 9 chosen because Attack on Titan made its debut in the inaugural issue of Bessatsu Shonen Magazine on September 9, 2009.

The move follows a similar recent development for Gundam, with April 7 officially designated as “Gundam Day,” suggesting formally recognized anniversary dates are becoming an increasingly common way for major anime franchises to mark their history in Japan.

The manga would continue running until April 2021, eventually reaching 139 chapters and becoming the foundation for an anime adaptation that introduced Eren, Mikasa, Armin and the wider conflict surrounding the Titans to an international audience.

September 9 had already effectively served as the series’ anniversary each year, including a major 15th anniversary celebration in 2024 that temporarily made all 139 chapters available to read for free and led to the release of a special anniversary magazine.

Its newly official status is being marked with a special “Attack on Titan Day” visual that makes particularly heavy use of the number nine, combining the September 9 date with imagery based around the Nine Titans.

The visual also introduces a dedicated “Attack on Titan Day” logo inspired by Eren’s enormous final Doomsday Titan form, which appears during the concluding stages of the story.

Kodansha has also revealed an official registration certificate confirming the new commemorative day, alongside three separate celebrations that will take place when the first “Attack on Titan Day” arrives on September 9, 2026.

The first continues the repeated use of the number nine, with Kodansha’s Magazine Pocket manga app making the first 99 chapters of Attack on Titan available to read for free for exactly 99 hours.

The campaign begins at midnight JST on September 9 and remains available until 2:59 AM JST on September 13, covering a substantial portion of the original 139-chapter manga.

A completely new merchandise collection will then launch on September 9 through Magazine Shop, the first permanent physical store dedicated to Weekly Shonen Magazine.

Products will use both the new Attack on Titan Day visual and original artwork drawn by Hajime Isayama specifically for the celebration, featuring Eren Yeager, Levi Ackerman and Erwin Smith dressed in formal clothing.

Full details of the individual merchandise have not yet been announced, although the newly drawn Isayama artwork gives the collection something beyond simply repurposing existing illustrations from the manga.

The celebrations will conclude later that evening with a special Attack on Titan livestream beginning at 9:30 PM JST.

The broadcast will reunite Eren voice actor Yuki Kaji, Mikasa voice actor Yui Ishikawa and Connie Springer voice actor Hiro Shimono, with Kodansha promising that the stream will feature plenty of new information relating to Attack on Titan.

Exactly what will be announced during the broadcast has not yet been revealed, while the streaming platform and further viewing details will be confirmed through the official Attack on Titan social media accounts closer to September 9.

With the date now formally registered, September 9 will continue as “Attack on Titan Day” beyond the 2026 celebrations, permanently linking the franchise’s annual anniversary with the day Isayama’s manga first appeared in 2009.