Yu-Gi-Oh! 5D's episode 18: "Return to the Spirit World, Part 1"
Kuribon is the Duel Monster Spirit of the card "Kuribon". She serves as Luna's spirit partner and often appears to her when anxious that something bad is about to happen. "Kuribon" is the female form of "Kuriboh".
Prior to pilot
Eight years after her first visit, Luna was sent to the spirit world. Here she met up with Kuribon, who assists in finding Ancient Fairy Dragon, who is sealed in stone and helps her remember the promise she made to protect the spirits.
The moves in Luna and Frank's Duel in the human world dictated what happened to the spirits. So "Gestalt Trap" was strapped to Kuribon, who was also affected by "Immortal Homeostasis". Kuribon was attacked by Ido. Kuribon was able to survive the attacks, but suffered pain, which Frank described as the "pain of immortality". The second time it was attacked, Luna managed to save Kuribon using "Fairy Wind" to free her from Frank's cards.
While the Signers and their companions pursued the Dark Signers, Kuribon appeared to Luna and told her there was trouble in the spirits' world. Luna's body and mind were transported to the spirits' world.
She and Kuribon went to the town, Schwank, where they were hunted by Zeman's monkey troop. Kuribon, along with the spirits of some of Luna's other cards distract the troop to allow Luna to escape. The monkeys cast a Minus Curse on the spirits, turning them into stone slabs of Duel Monsters cards with Negative Levels.