Sonozaki Family

The Sonozaki Family is an aristocratic family in Futo who created the organization Museum to produce and distribute the Gaia Memories in the criminal underworld, resulting in the Dopant crimewaves. They each own special golden Gaia Memories, allowing them to assume Dopant forms with the use of a prototype Gaia Driver belt, preventing the Gaia Memory's corruptive nature. Because they have belts, they are easily identified as "Commanders" by Shotaro and Philippe.

Ryubee Sonozaki
He is the head of the Sonozaki Family and leader of Museum, acting as a godfather in the organization. In his eyes, the entire city of Futo is his kingdom and he refuses to let his vision of it be ruined, seeing the Gaia Memories as humanity's next step in evolution regardless of the death of those unable to use them. Using the Terror Memory, Ryubee can assume the form of the Terror Dopant, whose very presence instills fear to those around him. Among his various abilities is to create a poisonous pool of liquid around the opponent before having it close in for the kill. True to the Dopant name, his very presence, even outside his Dopant form, can instill fear in others.

Saeko Sonozaki
She is the eldest of the Sonozaki children, running an IT company called the Digal Corporation and a figure in the events of Begins Night. From childhood, Saeko was raised under the notion by her father that their family is superior to all others and that they are destined to rule the world. However, she has bigger plans for the Gaia Memories that outweigh her duties to Museum. Using the Taboo Memory, Saeko can assume the form of the Taboo Dopant with the ability of flight and plasma sphere generation. Having a habit of doing away with her boyfriends out of her own disdain for weakness in others, Saeko spared Kirihiko and married him after. However, she abuses him when he fails to capture Kamen Rider Double in their fight with him. Later, when Kirihiko decides he can no longer support the family's goals, Saeko kills him for outliving his intended purpose.

Wakana Sonozaki
She is the youngest daughter of Ryubee who complains of the criticism she gets from her older sister, who despises her for being treated like a princess by their father. She puts up a public image as the shy DJ at the local Wind Wave radio station as the host of the Healing Princess radio show, having fans like Philip and Mikio (Shotaro is a fan until he sees her true self). She has the habit of performing a dental click when annoyed. Out of all of the Sonozaki family, she is the least involved with the production and distribution of Gaia Memories as Ryubee did not raise her to follow the family business like Saeko. With the Clay Doll Memory, Wakana can assume the form of the Clay Doll Dopant able to fire blasts of energy from her cannon-like forearms, adhere to ceilings, and reconstruct herself after being shattered to pieces. However, after the Violence Dopant incident and finding a kindred spirit in Philip, Wakana gets rid of the Clay Doll Memory. Ryubee later presents it to her, and she claims that she had lost it and was trying to find it.

Kirihiko Sonozaki
He is a young man who works for Ryubee, one of his best Gaia Memory dealers with a love for the city of Futo. Before being hired by the Sonozaki family and courting Saeko, he was a press agent, and in his youth he created the city's mascot Futo-kun. He marries Saeko, being noted as the only man she allowed to live after a date, changing his surname from Sudo. As Ryubee's way of accepting him into the family, Kirihiko receives a Gaia Driver and the Nasca Memory, allowing him to assume the form of the Nasca Dopant. As the Nasca Dopant, he wields a sword as his weapon along with his ribbons along with generating wings of energy and balls of plasma. When he reaches Level Two of his Gaia Memory's ability, he can move at blinding speeds. However, this carried an unintended side-effect as it slowly kills him.

Because he is an in-law, not being well trusted by Ryubee, Kirihiko does not know the full truth behind the Gaia Memories and is initially unaware of Double's existence until encountering the Kamen Rider personally and then fighting him face-to-face in a battle that ends in a stalemate. When first encountering Shotaro, he believes that the man is one of Wakana's stalkers. However, he eventually discovers that Shotaro is the Kamen Rider, seeing him as a rival keeping him from his goals and putting him of out good graces with Saeko until he secretly gains his Level Two abilities and uses them to save her from harm. However, after he discovers Museum's existence and how evil it truly was as he was used to test the full abilities of the Nasca Memory, Kirihiko could no longer support the Sonozaki Family. When he expresses this to Saeko, attempting to get her to leave with him, Kirihiko is killed by her as she takes Nasca Memory and leaves.

Mick
Mick is Ryubee's beloved pet blue British Shorthair. Despite being a cat, the Smilodon Memory can transform Mick into the humanoid Smilodon Dopant that can move at great speeds over great distances while discharging electric currents.

Third Child
A third child (a boy) of the Sonozaki family is frequently seen in flashbacks. This younger brother was a kind-hearted individual who was the voice of reason for Wakana. For reasons she is not quite sure, Philip reminds Wakana of her missing little brother.