|Japanese translated||Ikkaku Tachibana|
|Anime debut||Yu-Gi-Oh! GX episode 91: "Don't Fear the Reaper"|
|English voice||David Wills|
Lucien Grimley, known in Japan as Ikkaku Tachibana「橘一角」(Tachibana Ikkaku) is a Duelist who enters the Genex Tournament from North Academy. As a failing Duelist, Lucien makes a deal with the malevolent spirit of the forbidden and cursed "Grim Reaper" card sealed by the school, selling his soul to obtain incredible draw power.
In the English dub, Lucien makes death-related puns while using the "Grim Reaper".
The reaper imbues his right hand with the symbol of itself. Although he claims that his goal is to be victor of the Genex Tournament, his true wish was to experience a trusting bond with his Deck. He eventually loses to Jaden Yuki but promises not to lose trust in himself again. To that end, he threw the Reaper's card away, committed to winning without its assistance.
Lucien is also notable for being the first Duelist in the entirety of the Yu-Gi-Oh! anime series to be portrayed as left-handed or ambidextrous. He draws with his right hand while influenced by the Grim Reaper, but is able to switch to his left hand with ease.
Lucien plays a Reaper Deck, which uses various Spell Cards to force his opponents to automatically play or Set cards on the field. This allows Lucien to build up a certain number of cards on the field before he activates "Slash Draw" to instantly wipe out his opponents' Life Points after he draws another copy from his Deck. In the event that Lucien fails to defeat his opponent through a One Turn Kill, he will Summon "Invincible Demise Lord", who can revive itself with immunity to destruction by card effects when it is destroyed in battle, allowing it to survive the effect of "Slash Draw", which would destroy it under normal circumstances.