Rimuru's Demon Lord Form Headlines the Collab Roster
MIXI's word-battling mobile RPG Kotodaman is going back to the isekai well. The game's second collaboration with the That Time I Got Reincarnated as a Slime anime kicks off May 25 at 4:00 PM JST and runs through June 15, bringing seven new summonable characters headlined by Rimuru in his powered-up Octagram Demon Lord form.
The full collab summon lineup includes Rimuru (Octagram Demon Lord), Veldora, Shuna, Shion, Milim (Dragon Equipment), Ramiris & Beretta as a duo unit, and Luminous. All seven arrive as six-star characters with their original anime voice actors — Miho Okazaki as Rimuru, Tomoaki Maeno as Veldora, Rina Hidaka as Milim, and Lynn as Luminous among them.
On top of the new roster, the entire Round 1 collab summon pool is being revived. Players receive five free 10-pull tickets at login, with five more available through daily logins between May 26 and June 15 — enough for up to 100 free pulls on the returning banner.
Diablo Gets the Premium Treatment
The collab also introduces Diablo in his Demon Peer form as a paid pack exclusive. Buying the "Diablo (Demon Peer) Pack" unlocks the character immediately, and setting Diablo as your party leader during the event guarantees max-reward bonus drops on most collab quests — a perk normally reserved for fully upgraded units.
On the quest side, three TenSura antagonists join as collab bosses. Hinata, Mariabell, and Clayman round out the enemy lineup, giving players familiar foes to battle through during the three-week event window.
Campaigns and Giveaways
MIXI is running an X (formerly Twitter) campaign alongside the collab. Between May 22 and May 24, following both the Kotodaman and official TenSura anime accounts and reposting the campaign post enters players into a drawing for ¥5,000 in Eraberu Pay digital gift cards (10 winners). Posting with the hashtag #コトダマン転スラコラボ enters a separate drawing for a collab character set (5 winners).
Full event details are set to premiere during Kotodaman's official "GOD Station" broadcast on the game's YouTube channel on May 24 at 8:00 PM JST.
Looking Ahead
The collab's timing is no accident. TenSura's anime is in the middle of a major year — the second theatrical film, That Time I Got Reincarnated as a Slime the Movie: Blue Tears, hit Japanese theaters in February 2026, and Season 4 (a split five-cour run) started airing in April. The source light novel and manga have surpassed 56 million copies in circulation.
Kotodaman is available as a free-to-play download on iOS and Android in Japan. The game has no international release, so players outside Japan will need a Japanese app store account to participate. The collab runs from May 25 at 4:00 PM JST through June 15 at 3:59 PM JST.