COSM-GAME BrownDust2 Chained Soldier 2 Collaboration Begins
BrownDust2 begins its Chained Soldier 2 collaboration after maintenance on September 10, 2026, following the September 8 update notice from the BrownDust2 team. The limited collaboration Event Cassette remains available until the October 8 maintenance and introduces a crossover story involving the Mato Defense Force. The update also opens the Eternal Chains season event and adds collaboration characters and exclusive equipment.
Game summary
On this page
Chained Soldier 2 Arrives September 10
BrownDust2 starts its Chained Soldier 2 collaboration after the September 10 maintenance. The crossover is delivered through a limited Event Cassette that can be rented and played through October 8.
The collaboration also changes the app icon and title screen for the event period.
Note: The Chained Soldier 2 Event Cassette is temporary. It becomes unavailable when its rental period ends with the October 8 maintenance.
The Event Cassette Adds a Crossover Story
The collaboration story begins when monsters from the alternate space known as Mato appear in the Night World because of a dimensional distortion. Justia's group is unable to affect the creatures with its normal methods.
Kyouka Uzen, captain of Unit 7 of the Mato Defense Force, enters the Night World as the crossover develops. BrownDust2's cast then fights alongside members of the Mato Defense Force against the invading monsters.
The Event Cassette has no additional unlock requirement during its availability period, so eligible players can enter the collaboration story without clearing another special prerequisite first.
Eternal Chains Opens as the First Season Event
Eternal Chains runs from September 10 after maintenance until September 23 before maintenance. It is the first season event connected to the collaboration.
The event includes several established BrownDust2 activity types:
- Normal battles.
- Challenge battles.
- Fiend Hunter content.
- An event shop.
- Access through the collaboration Event Cassette.
Players earn event materials from participating in the event content and can exchange those materials through the event shop.
Kyouka Uzen Joins the Collaboration
Kyouka Uzen receives the collaboration costume Infinite Chain Kyouka Uzen. Its availability begins on September 10 and continues through October 8.
The collaboration event provides a route to strengthen the distributed Kyouka costume to +5. Kyouka also receives the exclusive gear Kyouka's Sword during the same collaboration period.
Tenka Izumo and the Collaboration Roster
Tenka Izumo is another featured Chained Soldier 2 character in the crossover and receives limited recruitment content with her exclusive Tenka's Earrings gear. Her collaboration costume is not scheduled to enter the normal Hope Powder or Selective Draw pickup routes after its limited period.
Ren Yamashiro is also part of the Chained Soldier 2 collaboration roster shown for the crossover. Together with Kyouka and Tenka, the Mato Defense Force characters connect the collaboration's character releases with the new Event Cassette story.
Collaboration Availability
The main Chained Soldier 2 Event Cassette remains rentable from September 10 after maintenance until October 8 before maintenance. Once that period ends, the cassette is automatically returned and its story can no longer be played through the temporary collaboration route.
Eternal Chains has a shorter schedule than the overall cassette period, so the season event closes before the main collaboration rental window ends. Recruitment, equipment and other limited collaboration content also follow their own published schedules inside the larger crossover period.
Trailer, screenshots, and media
FAQ
6 questionsThe Chained Soldier 2 collaboration starts after the September 10, 2026 maintenance. Its limited Event Cassette remains available until maintenance on October 8.
It is a limited collaboration Game Cassette containing the crossover story. It can be played during the collaboration rental period and is automatically removed after that period ends.
No additional unlock condition is required for the collaboration Event Cassette during its availability period.
Eternal Chains is the first season event for the collaboration. It includes normal battles, challenge battles, Fiend Hunter content, an event shop and access through the collaboration Event Cassette.
The collaboration features Mato Defense Force characters including Kyouka Uzen, Tenka Izumo and Ren Yamashiro. Kyouka and Tenka also receive limited collaboration costume and equipment content.
The collaboration Event Cassette runs from September 10 until the October 8 maintenance. Individual season-event and recruitment periods can end earlier, so their specific schedules should be checked separately.