His appearance depends on the medium regarding his design.
Manga/Elusiveness of the Fog
Kyosuke Mamo has straw like hair that covers his right eye and in Elusiveness of the Fog, it is shown to be a dirty blond. His chin has a similar style to Koichi Zenigata. In the manga, he has a light coat on top of his dark suit while in Elusiveness of the Fog it is a dark coat and scarf.
Beware the Time Machine!/Is Lupin Still Burning?
Kyosuke Mamo appears as a black haired man with a smooth chin wearing a blue suit and a red cape. His first appearance, he wears goggles concealing his eyes however in later scenes, he removes them. In Is Lupin Still Burning, he wears a purple coat.
While his backstory changes, the only consistency is that he is a time traveller where a descendant of Lupin III ruins his life and wants his revenge.
Please note that this based off the English translation that may have changes to the script.
Kyosuke Mamo was born on February 30, 2854 and was a Science fiction writer who went insane while researching the fourth dimension and made his own time machine. His father was a notorious villain however he was murdered by Lupin XIII in the year 2883 and his revenge is to kill every single one of the Lupin family throughout history.
While Lupin was trying to run away, he bumped into Kyosuke outside of a castle ruin. He was walking away however Lupin wanted to fight him, Kyosuke told him that he didn't need to face him as he could go back in time to kill Arsène Lupin to remove Lupin III from history and jumped away. This made Lupin scared.
Kyosuke travelled back in time to see Goemon Ishikawa XIII practicing his sword skills, he asked him whether it was the Kaei, Ansei or even the Meiji eras however it was the Showa Era. He got frustrated that it was the wrong year and wanted to clarify by throwing a sword near a scared Goemon. Goemon told him his name and that it was the 58th of the Showa Era (1983), Kyosuke told him that in the future that he will be a partner to Lupin III and laughed as he walked away.
Back to the present, Kyosuke appeared and removed one of the world's many Fujiko Mines from existence as he killed her ancestors. Both him and Lupin returned to the castle ruins, Lupin sat down and wanted to die in a fight with Kyosuke rather than disappear like Fujiko. He laughed as to him it was like a quality sci-fi movie, he also told Lupin that his ancestors were peasants who were unable to fight. Lupin's ancestor was Jirokichi who was a simple farmer and all it took is to kill him to remove the Lupin family tree, Kyosuke then laughed. Lupin surrendered but asked for a final request to see a picture of his sons, he replied that he has all the time in the world and went forward in time with his time machine to get a photo.
After Kyosuke got the photo, he was surprised to see two feudal Japanese people talking to each other. He asked a farmer whether it was the Kaei or the Ansei eras and he replied that it was August in the 3rd year of the Kaei era (1850). Kyosuke wonder where was the farm but the farmer told him that he was standing in it, he asked whether the farmer was Jirokichi who confirmed his idenity and whether he had a french bride. Jirokichi says that he is getting married to Milaine Lupin tomorrow and taking her family name.
As Kyosuke was about to shoot Jirokichi, he was murdered as he was sliced across his chest. He knew something was wrong, as Lupin and Daisuke Jigen take off their disguises, Lupin was going to tell Jigen and Goemon the correct year before his death.
Beware the Time Machine!
While his background was similar to the manga, there were some changes in the anime adaption.
Kyosuke Mamo was born on November 18, 1932 and was a scientist as well as a Sci-Fi writer. He received the Hugo prize and specialized in research of the fourth dimension of time and space. In 1966, he became insane and was hospitalized in a mental institute, he predicted that the Earth will be destroyed and built a time machine that he compared to Noah's Ark.
One night, he appeared to Lupin and gave him a prophecy that the thief will disappear in four days' time. With that, he went back to his glowing time machine.
After a successful heist of a gold statue, Lupin and Jigen arrive at a castle. The statue vanishes. At first, Lupin and Jigen think they'd misplaced it. Kyosuke arrives and warns him that more things will disappear. He tells Lupin that Lupin XIII had murdered his family on March 31, 2874. Lupin dismissed the matter, and reminds Kyosuke that doesn't have a 4th yet, never mind a 13th. He tells the mad stranger to get a life and drove off.
He heads into the fourth dimension. While Lupin dozes in a chair in his hideout, he hears the voice of Kyosuke tell him him that his time machine can go to the past, present and future and has seen what happened with Lupin XIII killing the Mamo clan that will happen in 900 years. Before disappearing, he tells Lupin his date of birth and goes away. Lupin dismisses the entire thing as a dream before Jigen and Goemon confirm this date of birth to him in the research they found, putting the master thief on edge.
Lupin returns to the castle to face him. Kyosuke tells him that fighting him is a waste of time, and that all it takes is to get rid of Arsène Lupin to remove Lupin III from history. He claims that Lupin only has three days to exist, To prove is ability to travel through time, Kyosuke goes back in time and kills the architect who built the castle.
As Lupin goes on a date with Fujiko to take his mind off of his imminent demise, Kyosuke manages to make the Homare racehorse and the truck driver disappear from history. Lupin marries Fujiko as a last desperate attempt, she vanishes. Knowing that he couldn't trick Lupin because Fujiko would have been a Lupin, Kyosuke takes Fujiko back to the past instead of killing her, and plans to return her after Lupin is gone.
After a while, Lupin returns to the church and requests to make two more wishes. Kyosuke thinks that "the great Lupin" has given up. Lupin begs to see Jirokichi of Kawamuko, Arsène Lupin's grandfather. Kyosuke wonders if Jirokichi was tough, but Lupin says that he was just a simple farmer. Lupin also requests that he see Fujiko again before taking out Jirokichi. He agrees and goes into the time machine.
Kyosuke returns with Fujiko, but is surprised to see a farmer plowing a field near a Japanese temple. He asks the farmer the year, and he replies that it's August in the 3rd year of the Kaei era (1850). Kyosuke believes the time machine had malfunctioned and it would be a costly repair. The farmer mentions that his name is Jirokichi of Kawamuko, and that he had to go to France to marry the "cutie" Mylène Lupin.
Kyosuke threatens the farmers and asks whether it was August in the 3rd year of the Kaei era. Goemon tells him it's actually the 47th year of the Showa era (1972). Lupin and Jigen remove their costumes and destroy the time machine. Kyosuke panics and flees.
Elusiveness of the Fog
It is revealed that the reason for him inventing a time machine and going back in time to kill Lupin is because Lupin XXXIII stole his girlfriend as he arrived at her house. In flashbacks, its shown Kyosuke was gifted at electronics at an early age.
In the end, Kyosuke Mamo is stranded in feudal Japan.
Is Lupin Still Burning?
Lupin and the gang enter the race to get the idol he stole from them in their first encounter. Kyosuke teams up with Mister X to alter time so Lupin doesn't have his allies and isn't famous anymore. He is defeated when Lupin's allies intervene despite not knowing who Lupin is. He and X are trapped in prehistoric times.
- In the manga, his time machine is not shown however in both Beware the Time Machine and Elusiveness of the Fog, it is a capsule.
- In "Beware the Time Machine!", his date of birth is given as November 18, 1932. This would mean that Kyosuke would have been 40 years old in the episode.
- He shares his English voice actor with the similarly named Mamo from The Mystery of Mamo, Paul St. Peter.