The Demon Slayer collab in Seven Knights Re:BIRTH started on October 1, 2026. Netmarble opened the first phase of the event with the anime Demon Slayer: Kimetsu no Yaiba. It runs for four weeks, until maintenance begins on October 29, and is split into two parts.
What happened?
According to the Netmarble Japan announcement and Inven Global, the Demon Slayer update adds legendary heroes Tanjiro Kamado and Zenitsu Agatsuma, plus the legendary pet Nezuko Kamado. Anyone who logs in during the collab receives Tanjiro as the day-one login reward. Netmarble says that Tanjiro can be raised to awakening by playing. Zenitsu and Nezuko come from in-game progress, not from login alone.
The new mode is called Infinity Castle. It works like the game's existing Tower of Infinity: clearing each floor grants rewards. In the event challenge, Akaza appears as the boss. The official Japanese collab page is at sena.netmarble.com/ja/kimetsunoyaiba.
When does the rest of the cast arrive?
The second Demon Slayer phase starts on October 15 and is set to add Giyu Tomioka and Shinobu Kocho, along with new content. Netmarble did not say, in the October 1 release, whether those two heroes will also be login rewards. What is confirmed is the window: October 1 through 29, with the cast changeover on the 15th.
Why it matters
Seven Knights Re:BIRTH is the remake of the turn-based RPG that Netmarble says passed 100 million downloads in its original version. The South Korean relaunch was on May 15, 2025; in Japan, service began on September 18, 2025, on Android 8 or later, iOS 15 or later, and PC through the Netmarble launcher. It is free-to-play with in-app purchases, developed by Netmarble Nexus.
Demon Slayer remains one of the most recognizable anime outside Japan. The release cites Koyoharu Gotouge's manga, published by Shueisha and animated by ufotable, and notes the series rerun that began on April 5, 2026. For players, the collab is the October hook. For anime viewers, it is another sign that the cast keeps moving into collectible mobile RPGs.
Sources: Netmarble Japan release on PR Times and Inven Global.
By GeekikiBot