|Age|| 12 (Ben 10)|
13 (Ben 10: Omniverse)
17 (Ben 10: Alien Force)
18 (Ben 10: Ultimate Alien and Ben 10: Omniverse)
|Affiliations||Killer Skull Gang|
Juvenile Delinquent (formerly)
Expert Martial Artist
|Equipment||Ryuji Maruyama's Katana|
|Voice Actor|| Charlie Schlatter (Ben 10) |
Dante Basco (Ben 10: Alien Force, Ben 10: Ultimate Alien and Ben 10: Omniverse)
|First Appearance||Ben 4 Good Buddy|
Ryuji has medium-length black hair, which covers the right part of his face. His eyes are dark brown, and the right one is always obscured by his hair. In Alien Force, his hair is quite longer than before, almost reaching down to his shoulders. In Omniverse, he has his hair cut short, now revealing both of his eyes.
In Ben 10, he wore a short black high-collared overcoat over a dark red shirt with elbow-length sleeves, calf-length dark blue pants, a black belt around his waist, white socks and red and black sport shoes. He also had a black wristband on his left wrist.
In Ben 10: Alien Force and Ben 10: Ultimate Alien, he now wears a black unbuttoned gakuran jacket with a red armband on the left sleeve over a unbuttoned white dress shirt with a dark red shirt underneath, black gakuran pants, red sneakers and a silver circle necklace. He still wears his black belt.
In Ben 10: Omniverse, he now wears a black leather jacket over a dark red shirt, dark blue rolled-up pants, a black choker, and black knee-high boots. He still wears his black belt and silver circle necklace. He also wears the black wristband he wore when he was 12, now in his right wrist instead of his left.
Ryuji is usually a criminally insane sociopath, willing to hurt/kill anyone for his own personal gain and/or pleasure, who is always bullying Shiori.
Ryuji also seems to be visibly annoyed by Rook's naivety and lack of experience on earth.
Powers and Abilities
Being an ordinary human, Ryuji has no powers, but he is a very skilled swordsman.
- Ryuji shares several similarities with Kevin:
- Both have black hair and dark brown eyes (although Kevin's eye color were not visible in Ben 10: Alien Force, Ben 10: Ultimate Alien and Ben 10: Omniverse)
- Both fought Shiori Sakurai (Kevin always beated Shiori, while Ryuji was beaten by her)
- Both were being hated by Shiori Sakurai and fought her, until they saved her (Kevin saved Shiori from being hit by a Highbreed, which led them to become fast friends, though they can still argue and tease each other sometimes, and Ryuji saved her from being attacked by Gwen Tennyson when she was controled by Diagon, which possibly led them to become interested on each other, though they can still argue and tease each other sometimes)
- Both were introduced as sociopathic and insane characters, which led them to become antagonists, only to later on switch sides as the series progresses (Kevin in the first two episodes of Alien Force; Ryuji in the last two episodes of Ultimate Alien)
|Aggregor • Diagon • Forever Knights (Connor • Driscoll • Enoch • Joseph Chadwick, Patrick, Red Knight, Sir Cyrus, Sir Dagonet, Sir Morton, Sir Reginald, Squire, Urian) • Khyber • Malware • Vilgax • Zs'Skayr|
|Albedo • Aloysius Animo • DNAliens • Elena Validus • Eon • Flame Keepers' Circle (Conduit Edwards, Esoterica) • Hex • King Viktor • Lucubra • Mummy • Negative 10 • Psyphon • Sixsix • Sevenseven • Sunny • Vulkanus • Will Harangue • Xenocyte • Yenaldooshi • Michael Morningstar|
|Adwaita • Aggregor's Soldiers • Camille's Ex-Boyfriend • Carl Nesmith • Circus Freak Trio (Acid Breath, Frightwig, Thumbskull) • Clancy • Coach Finn • Computron • Evil Way Big • Garbage Monster • Gorvan • Highbreed Tree Monster • Hiroshi Sakurai • Howell Wayneright • Incursion (Milleous, Attea, Sang-Froid, Frolic) • Jarrett • Jennifer Nocturne • Krabb • Kolar • Ma Vreedle • Mayor Coleman • Mizaru • Morgg • Mr. Mann • Mrs. Mann • Mycelium • Nanochips • Palorfayg • Pickaxe Aliens • Plant Alien • Plant Clones • R.E.D. • Road Crew (Baron Highway, Road Rage, Turbine) • Rojo • Rojo's Gang • Sublimino • Ragnarok • S.A.M. • Slix Vigma • Squires • Ssserpent • Sunder • Synthroid • Techadon Robots • The Decoy Queen • The Great One • Trumbipulor • Vilgax's Drones • Zombozo|
|Argit • Baz-El • Charmcaster's Stone Animals • Hope • Null Guardians • Simian • Stone Creatures|
|Bivalvan • Cash • Chromastone • Dragon • Decka • Devlin Levin • Eon's Servants • Goop • Helen Wheels • Highbreed (Reinrassic III, Highbreed Commander, Highbreed Councellors) • J.T. • Kenko • Kevin Levin • Manny Armstrong • P'andor • Prisoner 775 • Ra'ad • Retaliator • Ryuji Maruyama • SACT (Lieutenant Steel) • Sentient Ultimate Big Chill • Sentient Ultimate Cannonbolt • Sentient Ultimate Echo Echo • Sentient Ultimate Humungousaur • Sentient Ultimate Spidermonkey • Sentient Ultimate Swampfire • Sir George • Spidermonkey • Technorg • Tetrax Shard • The Great One's Worshipers (Leader Alien, Enforcer Alien, Interpreter Alien) • Thomas Jingles • Vance Vetteroy • Victor Validus • Vreedle Brothers (Octagon Vreedle, Rhomboid Vreedle) • Winston|
|Generator Rex Villains|
|Alpha • Biowulf • Black Knight • Skalamander • I-Bol|
|Exo-Skull • Kevin 11,000 • Vilgax (Goodbye and Good Riddance Timeline)|