Abyssbell, also known as the Jashin Emperor or Jashin-kun, is an ancient and immensely powerful entity from the Darkness civilization. He is a ruler of the Abyss Royale race who claims to have slumbered for ten thousand years before being awakened. His presence is linked to the Boundary Line, a mysterious divide separating the ordinary world from a devastated alternate reality. After Win Kirifuda encounters the Boundary Line, Abyssbell contacts him with a cryptic warning: the duel to take everything back will begin soon. He appears to Win as a mysterious voice from the shadows and becomes his signature ace creature card, forming a cooperative bond in which both duelist and creature are needed for true victory. In the LOST arc, where Win suffers from amnesia, Abyssbell serves as a guide from the shadows, helping the protagonist navigate a dangerous world and recover his lost past. He shows familiarity with the human world, including the dark web’s illicit Demon Lord network where supernatural artifacts are traded, and he monitors widespread murders linked to Ballom that appear connected to a contract with a figure named Kyoshiro. He is also tied to the powerful Crystal Card entrusted to Win by Crysta, an item valued at fifteen billion yen on the dark web. In duels, his abilities include granting Abyss Rush to Abyss creatures in the graveyard, reducing their summoning cost, avoiding departure from the battle zone by discarding two cards, and functioning as a blocker with double breaker.