Imori, named Damien Draco in the English version of the DDM video game, is a student at Domino High School. Withdrawn and somewhat shy, Imori is then revealed to be anti-social and selfishly vindicated, akin to being Yugi's own evil counterpart, eventually uncovering the secrets of Yugi's Millennium Puzzle, and decides to usurp Yugi Mutou from his position of the guardian of darkness by challenging Yugi to a game of Dragon Cards, a forbidden game which his grandfather found while in Manchuria in World War II. Imori wins the first game against regular Yugi, causing his soul to go into the soul-eating jar. Regular Yugi's last minute grab for the puzzle causes Dark Yugi to come out. The second Dragon Cards duel ends with Imori losing. In the manga, Imori's soul gets sucked into the soul-eating jar, to be eaten by twenty-five dragons. Yugi's soul comes out and is re-absorbed into his body unharmed. In the first series anime, Imori played Dragon Cards (remade as Dragon Block) at his house instead of at school, and only the dark part of Imori's soul was eaten.

He is referenced in Yu-Gi-Oh! GX, when his name is listed among Trueman's victims. This scene also reveals his first name to be Hajime. In the first anime, Imori's personality is a lot different from in the manga, In the manga Imori was rotten to begin with, while in the first series anime he was often bullied by others which caused him to feel worthless. When Yugi Mutou saves him from some thugs they become friends, Later, When the same bullies knock the Dragon Block out of Imori's hands breaking the seal Imori's Dark side emerges and he seals one of the thug's soul in the Dragon Block. When Imori's darkside was sealed into the Dragon Block it is assumed that the bully's soul is salvaged from the Dragon Block as only one soul can be devoured by the twenty five dragons at a time.

Imori bears a slight resemblense to Bonz from the manga, and second series anime.