Impmon is a Digimon without a Tamer who is living in the human world.
He wrap digivolves to Beelzemon.
Impmon is a small humanoid imp creature with a tail and large pointed ears. He wears a pair of red gloves and a matching red bandanna.
He is selfish, cocky, greedy, loud-mouthed and aggressive and love causing trouble for the Tamers.
He also has an ego and is proud of being a free agent, mocking everyone else and trying to act superior. Although he's obviously a bad guy, his meanness is of a funny sort - he's not big and scary and trying to demolish large buildings. He does push his luck though, stretching the patience of Digimon stronger than him.
It is reaval that Impmon is in fact the Digimon partner of two children: Ai and Mako. Impmon ran away from the two after they continuously quarreled over him, treating him as if he were a toy.
Impmon resents the Tamers and their Digimon because they, unlike him, are able to digivolve. He tries to prove himself by fighting Indramon, despite Renamon's warnings, but suffers a devastating and painful defeat. Being humiliated and having his ego crushed, Impmon readily accepts the Caturamon's offer. Impmon would gain the ability to digivolve, but, in return, Impmon would have to kill the Tamers and their Digimon. He is very conflicted by this at first, remembering the kindness Guilmon would show Impmon despite his constant insults, but he still accepts, desperate to digivolve.
Impmon is granted the power to become Beelzemon, and blinded by the power, goes down a murderous path. He begins destroying virtually anything that comes in his way, eventually killing Jeri Katou's partner Leomon, triggering a battle that nearly ends in his destruction as retribution for Leomon's death. He is spared at the last moment by Jeri, her reasoning being that while she hated him for what he did, she didn't want to see anymore lives be lost. Shaken by this display and considerably weakened from battle, he wanders off, now guilt-ridden and ashamed of his horrific deeds. He de-digivolves into Impmon again after being attacked by a group of Chrysalimon, whom he allows to attack him because he no longer wanted anything to do with the power that he formerly so reveled in, and is essentially left to die. Luckily, he is found by Renamon and Rika Nonaka, who decide to bring Impmon back into the Real World. After being not only spared, but saved by the people he had once hated and tried to destroy, Impmon eventually resolves to try and make right all the wrongs he'd committed towards others, especially Jeri and the other Tamers.
With new goals in mind, Impmon returns to and reconciles with Ai and Mako, who, to his surprise and joy, not only welcome him back with open arms, but tell him that they will do anything to convince him to stay with them, even stop fighting. Touched by their display, Impmon finally admits (to as much himself, as well as to them) that he loves them. When the D-Reaper finally appears in Shinjuku, Impmon leaves to help the others. Ai and Mako send him their best wishes and a small toy gun, with which he becomes Beelzemon Blast Mode. With this upgrade, he turns the tide of battle and finally seems to accept the other Tamers and Digimon as his friends.
While at Takato's school, Impmon encounters Calumon and after learning Jeri's in trouble, joins with him to rescue her. He digivoves to Beelzemon: Blast Mode to fight D-Reaper's agents and after an unsuccessful attempt to rescue Jeri with Gallantmon's help, is badly injured and reverts to Impmon, only surviving because Grani rescues him. Later, on a bus out of town, Impmon believes he will die of his injuries and Ai and Mako's care for him cause them to get a D-Ark and become his offical Tamers.
After the D-Reaper's destruction, Impmon is at last able to ask Jeri for forgiveness. To his relief, she agrees, leaving Impmon finally at peace with the humans.
Digimon Tamers The Movie: Runaway Locomon
A few months later, after Parasimon's defeat, he attends Rika's birthday party at the end, scarfing down food throughout the party.