Backstabbed in a Backwater Dungeon Anime Reveals Main Trailer with Tei’s Opening Theme
The highly anticipated dark fantasy series Backstabbed in a Backwater Dungeon has released its main trailer, previewing the opening theme song performed by anime music artist Tei. The TV anime, adapted from Shisui Meikyo’s light novel, premieres in Japan on October 3, 2025, with animation by J.C.STAFF.
xboxgaming
The official website for the upcoming fall 2025 TV anime Backstabbed in a Backwater Dungeon: My Trusted Companions Tried to Kill Me, but Thanks to the Gift of an Unlimited Gacha I Got LVL 9999 Friends and Am Out for Revenge on My Former Party Members and the World has unveiled its main trailer.
The trailer highlights the voices of the main cast—Mei (Ikumi Hasegawa), Nasuna (Hana Hishikawa), Aoyuki (Shiori Izawa), Ellie (Ayumi Mano), Nemumu (Yuko Natsuyoshi), and Gold (Katsuya Miyamoto). It also debuts the anime’s opening theme song, performed by singer-songwriter Tei.
Tei’s New Theme Song
Known both as Tei Hinoto (mini-harp singer-songwriter) and simply Tei (anime theme performer), the artist has contributed opening songs for Tsurune (2023), The Weakest Tamer Began a Journey to Pick Up Trash (2024), and Unnamed Memory (2024). Their new track for Backstabbed in a Backwater Dungeon will be released digitally on October 4, 2025.
Tei commented on the song’s creation:
“As I read through Light’s journey of betrayal and revenge, I realized this story required not just empathy, but strength to guide the protagonist’s resolve. I put my heart into this song, hoping it deepens the emotional weight of the anime.”
Anime Premiere & Staff
The anime is based on the fantasy light novel series by Shisui Meikyo (story) and tef (illustrations). It is scheduled to premiere in Japan on October 3, 2025.
Key production staff includes:
-
Director: Katsushi Sakurabi (Is It Wrong to Try to Pick Up Girls in a Dungeon?: Arrow of the Orion)
-
Studio: J.C.STAFF
-
Series Composition: Hiroshi Onogi (Fullmetal Alchemist: Brotherhood)
-
Character Designs: Yukie Suzuki (TSUKIMICHI -Moonlit Fantasy-)
-
Music: Ryo Takahashi (WIND BREAKER)
-
Sound Director: Yoshikazu Iwanami
Story Synopsis
The anime follows Light, a once-trusted companion betrayed and left for dead by his former allies. Escaping to the perilous Abyss dungeon, he discovers the true power of his seemingly useless Unlimited Gacha skill. Instead of junk items, the gacha summons Mei, a stunning Level 9999 warrior. Over three years, Light builds a hidden kingdom with powerful allies who pledge loyalty to him. Now a Level 9999 Overlord, Light begins his mission of vengeance—determined to destroy those who betrayed him and reshape the world.
With its dark themes of betrayal, revenge, and overpowered allies, Backstabbed in a Backwater Dungeon is set to become one of fall 2025’s standout fantasy anime releases.
