Mameo

Mameo (マメオ), originally known as the Black Knit Cap Man (黒いニット帽の男), is a mysterious man. His true name is unknown, but Luche calls him Mameo because of the Mamemon print on his hat, and he himself adopts the nickname afterward.

Appearance
Mameo is a young man with fair skin, brown hair and blue eyes. He wears a black knitted hat with a white Mamemon smiley face on it, a yellow and black hooded shirt with long sleeves, black pants with yellow pockets, and black sneakers with yellow soles.

Description
Mameo carries a that was presumably his partner Mamemon. Unfortunately, it is stuck in that form due to the BH Program.

Digimon World
The Protagonist lives in Tokyo with his mother.

One day, he goes to the park and sees his friends playing Digital Monster in a battle between MetalGreymon and MetalMamemon. After arriving home, he finds his mother's note, saying she would arrive home late, and hears a sound coming from his Digimon Pendulum, where a Koromon is calling him. He is then dragged to the Digimon World.

After waking up in the Digimon World, the Protagonist thinks he's dreaming, but then Jijimon tells him it's not a dream, and shows him his Partner. Inside his house, Jijimon tells the boy that he brought him to the Digimon World to save File Island, as its inhabitants were losing their memory. He then asks the Protagonist to take his Partner to explore the island, find the cause of the danger, and get Digimon to come back. The Protagonist then recruits a large amount of Digimon, then goes to Mt. Infinity to confront the antagonist, Analogman and his partner Machinedramon. After defeating them, Analogman attempts to blow up the Island, however he is thwarted by Airdramon and his bomb only winds up causing his own death. Despite this, Analogman is able to return, either in Gray Lords Mansion, Ogre Fortress or Ice Sanctuary - which then transforms into the Back Dimension - with an even stronger Manchinedramon, though ends up losing again. It is then it is found out that the Machinedramon was a fake, created from an ordinary Digimon. This same event happens over and over again in an endless loop.

Digimon Digital Card Battle

The protagonist of the game uses the appearance of the main character from World, where he once again defeats Analogman, who this time tries to end the world using the Digimon card game. He is once against thwarted by the hero.

Digimon World -next 0rder-
He first appears in Server Desert, trying to restore a Gotsumon that had been infected by the BH Program with a basic antivirus, but fails. Shiki/Takuto, Kouta and Himari come across him while he does this, and assumes that he is the human behind the unexplained Machinedramon attacks. After the protagonist defeats the Machinedramon, he introduces himself and his partner, who is stuck in Digiegg form because of the BH Program infecting it.

Brought back to Floatia, he explains that he was attempting to remove the infection, but failed. He passes on his prototype antivirus to the protagonist. The protagonist uses the antivirus to cure multiple Digimon until a more powerful form is made. Once the player defeats Shoma Tsuzuki and Omegamon Alter-B, Mameo mentions that "the man he defeated once before" (Analogman) had been possessing Shoma and that Shoma was not to blame for anything that had happened. Shoma disagreed though, saying he sought out the power and that it was his fault. We later learn that Mameo is a teacher in the real world and is Shoma's home room teacher.

Mameo then returns to being a tamer and battles the player with his reborn Mamemon and his new partner, a Machinedramon.