That Time I Got Reincarnated as a Slime season 3 episode 23: The Dungeon trial ends Rimuru's Founder's Festival on a high

That Time I Got Reincarnated as a Slime season 3 episode 23, titled The Labyrinth's Grand Opening, was released on September 20, 2024, on Nippon Television in Japan. In this episode, Rimuru Tempest's executives unveiled the Dungeon on the third day of the Founder's Festival.

From Eren to Basson to Masayuki, several adventurers entered the Dungeon and confronted various challenges. Mjollmille and Shoka also revealed interesting facts regarding the Dungeon. With that, That Time I Got Reincarnated as a Slime season 3 episode 23 concluded the Founder's Festival final grand event.

Disclaimer: This article contains spoilers from That Time I Got Reincarnated as a Slime season 3 episode 23.

That Time I Got Reincarnated as a Slime season 3 episode 23: Shoka and Mjollmile summon the adventurers for Dungeon exploration

That Time I Got Reincarnated as a Slime season 3 episode 23 commences with Shoka and Mjollmille introducing the audience to the Founder's Festival's next attraction, the Dungeon. They plan to reveal only a small portion of the vast Dungeon for advertisement purposes.

From the spectator's corner, Ramiris demonstrates her magic to erect the Dungeon's door. Shoka then introduces the audience to the groups of adventurers, who will participate in the Dungeon. The first group is Team Great Lightning, led by Basson, followed by Eren, Kaval, and Gido.

Shoka introduces Masayuki's party (Image via 8Bit)

The third group is none other than Masayuki the Lightspeed Hero's party. Interestingly, Gaiye also decides to participate in the Dungeon's challenge alone. However, his flashy entry and offensive remarks to the Big Four infuriate Rimuru's executives, but Slime tells them to let it slide.

After introducing the participants, Shoka announces that the progress of each party will be shown live through large screens. She also reveals that dryads will accompany each party to guide them in the Dungeon. Following that, That Time I Got Reincarnated as a Slime season 3 episode 23 shows Shoka explaining the rules to everyone.

Gaiye, as seen in the episode (Image via 8Bit)

There are several items available for purchase before entering the Dungeon. Shoka and Mjollmile recommend the Resurrection Bracelet as it allows the adventurers to respawn/revive if they die inside the labyrinth. They add that the ring's power only works inside the Dungeon, not outside.

Gaiye doesn't buy it, so he asks Mjollmile to demonstrate the ring's powers. That Time I Got Reincarnated as a Slime season 3 episode 23 then shows Gaiye brutally killing Mjollmile inside the Dungeon as a test. The audience is stunned as the merchant revives outside the Dungeon.

That Time I Got Reincarnated as a Slime season 3 episode 23: The Dungeon's trial begins

The narrative for That Time I Got Reincarnated as a Slime season 3 episode 23 begins with the Dungeon's exploration, as the brave challengers confront various challenges inside. Basson's team falls to a minor trap on the first floor, set by Ramiris.

Rimuru learns from the Pixie that she tinkered with the Dungeon's construction after its final design. However, while Basson's team falls into the trapdoor, Eren and others easily bypass them and find a chest item sooner than anyone.

Rimuru and Ramiris in the episode (Image via 8Bit)

Ramiris apologetically reveals to Rimuru that she spilled the location of the Dungeon's secret traps to them in exchange for a cake. Meanwhile, That Time I Got Reincarnated as a Slime season 3 episode 23 reveals that the Dungeon has three types of treasure chests in all: bronze, silver, and gold.

While gold chests offer premium items, they only show up on the boss floors (multiple of ten). Mjollmile further reveals that the Dungeon has a total of 100 floors. Veldora remains stationed on the final floor, while Boyix has been given the duty of being the boss of floor 50.

Masayuki, as seen on the giant screen (Image via 8Bit)

The narrative for That Time I Got Reincarnated as a Slime season 3 episode 23 then switches the focus to Masayuki's party as they cruise through the Dungeon and make it to the fourth floor within 30 minutes. Likewise, Gaiye moves to the second floor, focusing on heading straight for the stairs.

Rimuru wonders whether Gaiye has any magic items or such to get information on his location. The Great Sage reveals it's due to the adventurer's Elemental Magic Automap. On the other hand, Veldora wonders how he should approach the adventurers once they enter the final floor.

That Time I Got Reincarnated as a Slime season 3 episode 23: Eren and Masayuki's teams press deeper into the Dungeon & conclusion

Veldora, as seen in the episode (Image via 8Bit)

That Time I Got Reincarnated as a Slime season 3 episode 23 shows Basson's team failing horribly to predict the traps inside the Dungeon. Even if they die and revive multiple times, they continue to push on. Likewise, Team Kaval ventures into the deeper floors after collecting enough potions.

Mjollmile wonders whether they want to find the rare items. Apparently, the only way to acquire those items is from the gold chests found in the designated boss chambers. Besides those boss floors, Mjollmile recalls that "area bosses" that govern certain floors may also have them.

Eren's team gets the Tempest Sword (Image via 8Bit)

Rimuru finds out from Ramiris that she has leaked the locations of those area bosses as well. Eren's team finds one such floor and combats a group of bat monsters. After defeating them, they find a golden chest and acquire the legendary Tempest Sword.

Following that, they return outside and reveal how fun the Dungeon actually is. Eren's team's performance encourages other adventurers among the spectators to consider entering the Dungeon. Meanwhile, Masayuki's party confronts a boss monster. Jinrai easily defeats the boss and acquires a rare item from the golden chest.

That Time I Got Reincarnated as a Slime season 3 episode 23 then shows Gaiye reaching the same floor. However, he finds out that a boss monster respawns every 30 minutes. He becomes infuriated and orders the dryad in charge to resurrect the monster as soon as possible.

Gaiye's indecent behavior leads the Dryad in charge to eliminate him from the Dungeon. While he revives outside, he appears in an unconscious state. Following the Dungeon's trial, Rimuru Tempest delivers a speech about how he wants to officially open it in the near future.

He guarantees everyone about its safety. Rimuru also assures everyone that whoever manages to reach the final floor will get the right to challenge him. With that, the Dungeon's unveiling event comes to a close.

The final night of the festival ends with a grand banquet. Everyone, from monsters to humans, dances together and enjoys the night, exactly how Rimuru envisioned. However, Rimuru knows there's one thing left to be resolved. That Time I Got Reincarnated as a Slime season 3 episode 23 ends with the Slime planning to sort out the gold coin payment's due date.