Luppi used to be the sixth strongest Arrancar in Aizen Sōsuke's Espada, before being killed by Grimmjow.
Luppi used to be ranked sixth in Sousuke Aizen's Espada, meaning that he was the sixth most powerful among their group of ten, to not mention the sixth most powerful of all Arrancar. The original sixth Espada, Grimmjow Jaegerjaques, accidentially led a group of Arrancar to their deaths while trying to exterminate beings with high reiatsu (i.e. spiritual power) and as a punishment for doing this and disobeying orders his arm was severed and burned by Aizen's subordinate Kaname Tousen. No longer suited as an Espada, Grimmjow was demoted and Luppi took his place as the Sixth.
Later on, Aizen sent a group of Arrancar to the human world, with a mission to fight Soul Reapers and humans with high reiatsu. The group consisted of Luppi, Grimmjow, Yammy, and the newly reborn Arrancar called Margera Wonderweiss. Grimmjow immediately went elsewhere, while the rest of them encountered the four Soul Reapers Toshiro Hitsugaya, Rangiku Matsumoto, Ikkaku Madarame and Yumichika Ayasegawa. Luppi introduced himself as the Sexta Espada, and after fighting Yumichika he decided to release his Zanpakutou and fight the four Soul Reapers at the same time. After seemingly defeating Hitsugaya, he turned his attention to the other three, and successfully trapped them in his tentacles (the power of his released form). Urahara, who suddenly appeared on the scene, then sliced off one of the tentacles when Luppi tried to impale Matsumoto on his spikes. After complaining on how Yammy got to fight Urahara instead of himself, continued to talk to the Soul Reapers about how pathetic they were. Soon, Hitsugaya was revealed to have been alive and prepared an attack, and Luppi was relatively easily trapped in Sennen Hyourou ("thousand year ice prison"). Before Luppi managed to get out of the ice prison, the Arrancar were brought back to Hueco Mundo, more precisely Aizen's lair Las Noches.
At Las Noches, it was shown that the Arrancar mission was only a distraction for the Soul Reapers, and that Aizen's true goal was finding Orihime Inoue and forcing her join them, due to her extremely useful healing abilities. Luppi was not at all happy about that, since he got injured badly on what was only now revealed to be a cover mission. Aizen then told Orihime to demonstrate her healing ability by regenerating Grimmjow's arm. Luppi stated that doing something like that would be impossible, but also told Orihime that if she failed, she would die by his hands. When Orihime successfully regenerated Grimmjow's arm, she also removed the burn that hid his tattoo that symbolized his former position as the Sixth Espada. Almost immediately, Grimmjow punched a hole through Luppi, effectively killing him and reassuming the once lost position as the Sixth Espada.
Luppi has a tendency to talk and complain a lot, no matter the situation. He is also overconfident or arrogant, as seen when he decided to fight four Soul Reapers at the same time. He tends to not think too highly about people with lower ranks, and teased Grimmjow about not being the sixth Espada after he himself took over that position.
Luppi, in released state.
Luppi has black hair, grayish purple eyes and is quite thin. He has a generally feminine appearance, and his white Arrancar clothes seem to be a couple of sizes too large. The remnants of his hollow mask is located at the left side of his head and seems to be a top row of teeth. The number six is tattoed on his right hip, to signify his status as the sixth Espada.
The name of Luppi's Zanpakutou is Trepadora ("climber", a vine that climbs; in Spanish) and in released state, Luppi grows eight tentacles from his back that he can control independently to fight enemies. The tentacles can also grow spikes to impale enemies.