Yuji Kuroshima A warrior who wields a green sword and transforms into Kamen Rider Weapon. He speaks politely to everyone. He can transform into his strongest form, Kamen Rider Maximum Weapon Ultima Sword Custom (with the side effect of being unusable for 24 hours after one use). He has a strong sense of justice but possesses a somewhat childish personality and manner of speaking. He was actually a clone created by Yasunori Kamigori, but he has managed to overcome that fact. First person: I (casual). He calls Katsuro "Senpai" and Tatsuya "Tatsuya." He belongs to the organization ICF. He has a younger sister named Misaki Kuroshima.

Katsuro Samejima A warrior who wields a lime-green machine gun and transforms into Kamen Rider Armed. He can transform into his strongest form, Kamen Rider Armed Magma Chainsaw Custom (with the side effect of being unusable for 24 hours after one use). He is Yuji's reliable senior at their part-time job (a convenience store). First person: I (casual). He rarely uses polite speech but is kind. He calls Yuji "Yuji" and Tatsuya "Tatsuya." He belongs to the organization ICF. His father and mother were killed by different individuals (his father by Dova and his mother by Gondola). Dova and Gondola have already been defeated.

Tatsuya Maeda A warrior who wields a long spear and transforms into Kamen Rider Assassin. He can transform into his strongest form, Assassin Blizzard Scythe Custom (with the side effect of being unusable for 24 hours after one use). Originally an enemy, he reformed after being persuaded by Weapon. First person: I (casual). He has a harsh way of speaking. He calls Yuji "Yuji" and Katsuro "Katsuro." He belongs to the organization ICF. Because he was kidnapped by the Murder Empire as a child, he occasionally acts a bit childish, but he is generally a reliable person with a slightly prickly (tsundere) personality; he is particularly compassionate toward his allies.

The original Yuji Kuroshima (called L-Yuji by those around him). A warrior who wields a black sword and transforms into Kamen Rider Lethal Weapon. He can transform into his strongest form, Kamen Rider Maximum Lethal Weapon Ultima Sword Custom (with the side effect of being unusable for 24 hours after one use). Initially an enemy, he reformed and became an ally after losing to Weapon once. First person: I (casual). He has a harsh way of speaking. He calls Yuji "Fake," Katsuro "Fake's Senpai," and Tatsuya "Assassin." He belongs to the organization ICF. He used to have a violent and rude personality toward others, but he became a bit kinder after meeting Yuji and the others (stopping his violence and verbal abuse).

Snake (a robot created by Kamigori). An ally to Weapon and the others who transforms into Kamen Rider Assault. First person: I (feminine/casual). She speaks with a regional drawl (Kansai dialect). She calls Yuji "Yuji," Katsuro "Katsuro," and Tatsuya "Tatsuya." She belongs to the organization ICF. She can predict the opponent's actions with her abilities, but she cannot predict the movements of Riders she has never seen before. She can transform into Perfect Custom, which uses both a gun and a sword (this form has no specific side effects).

The second Emperor of the Murder Empire. An enemy of Weapon and the others who seeks to destroy the world. He lives in a world different from the human world. First person: I (casual). He refers to them as Weapon, Armed, Assassin, Lethal, and Assault respectively.