Lucifer is featured as a boss and Lady Tremaine's cat in Kingdom Hearts Birth by Sleep and Kingdom Hearts Birth by Sleep Final Mix. In the game, Lucifer is on a self-assigned mission to keep Ventus and Jaq from collecting materials for Cinderella's ball gown.
Lucifer is a fat cat with dark brown fur covering most of his body. The fur on his belly, his paws, and the tip of his tail is tan. The fur on his head is ruffled and black. Lucifer's eyes are green and his sclera are yellow, while his nose is pink. He has two whiskers on either side of his upper lip.
Lucifer is shown sleeping in Lady Tremaine's room next to the last pearl (which he may or may not be guarding) for Ventus to gather for Cinderella's gown. As Ventus takes it and creeps back for the Mousehole, Lucifer wakes up and prepares to strike Ventus from behind, but Jaq warns Ventus at the last minute and throws balls of yarn at Lucifer to distract him. Lucifer rams himself into the cabinet where Jaq was standing, causing Jaq to fall onto the floor.
As Lucifer corners and prepares to kill Jaq, Ventus intervenes and strikes Lucifer's paw. Angered, Lucifer engages Ventus in a battle, which Ventus wins. Lucifer subsequently runs off and is not seen again.
Lucifer is Ventus's second boss. Fighting Lucifer head-to-head is tricky, although, if you take a hit, you can recover from the knockdown with Payback Raid. Strike from behind and use your Shotlock whenever possible. For most of the battle he attacks with his claws and sometimes jumps down from a higher part of the room, creating a shockwave as he lands. He also attacks by charging at Ventus.
Note that after using any of these attacks, he is left wide open. Simply dodge his claws and body slams and attack. With the right timing, a series of Reaction Commands will begin, which consists of Ven riding Lucifer like a bull. The player must enter various commands to hang on until Lucifer rams his head into a piece of furniture. Then, with the right timing, attack Lucifer with a Reaction Command called "Bronco Strike" while he's stunned, dealing massive damage. If you follow these techniques, then Lucifer should fall quickly and with relative ease.
Lucifer himself has no special powers of his own, but he mainly attacks by using his claws. He is quite agile, able to leap from higher parts of the room to body slam opponents. He can also charge at Ventus if angered.
Lucifer is a ferocious cat from the 1950 Disney film, "Cinderella". A nemesis to Cinderella's mice friends and the other animals living on Lady Tremaine's estate, he is pampered and praised by the elderly lady. While the two stepsisters and the wicked stepmother fail to realize Lucifer's evils, he never manages to avoid the protective and watchful eyes of one person, Cinderella herself.
She has a secret weapon used for dealing with the devious cat, however; her loyal dog Bruno. At the film's climax, he again tries to catch both Jaq and Gus while they are trying to free Cinderella from her locked room, but the birds see this and summon Bruno, who rushes to the mice's rescue and scares Lucifer out of the house.
- Lucifer was the very first Disney Boss revealed to appear in Kingdom Hearts Birth by Sleep.
- Despite his journal entry giving him the name "Lucifer", his name is never pronounced correctly in the game, to the point that even Ventus refers to him as "Roosifee", due to the fact that this is how Jaq pronounces it.