"I... believed in you. Komon-kun, I know you would be able to protect everyone."
- ―Riko's words in Komon's memories.
One year prior to the series, Riko was an artist and the girlfriend of Kazuki Komon. However during the night when they started dating, Riku and her family were assaulted by Nosferu. While her parents and younger brother were killed by the Space Beast, Riko was murdered in cold-blood by Shinya Mizorogi, who had already merged with Dark Mephisto. Riko was revived afterward and became a puppet to host the female Dark Giant, Dark Faust.
As Faust's battles with Ultraman Nexus grew more violent, Mizorogi began to erase her memories, slowly driving her insane with her unsealed memories of death. When Komon and Himeya found her, Riko was seemingly all gone and she transformed into Faust. Faust and Nexus erected their subspace fields, but Komon was also pulled into their private battlefield. Using him as a sort of hostage Faust overpowered Nexus and began to drain his energy. Komon, unable to accept what became of his beloved, shot at the dark giant while calling Riko's name, reawakening her and vanquishing the giant. Mizorogi, angered at the turn of events, summoned Nosferu to kill Komon.
At the last minute Riko jumped over Komon, taking the blow to her back. The space beast was destroyed by Nexus but the damage was done. Komon found Riko's dying form. After telling him she loved him, she dissipated into particles of Light. Later on, Mizorogi would use her image as one of his illusions to torment Komon and to turn him to the dark side, only to be driven away by Komon's own light from his love and memories of Riko. When Ultraman Noa defeated Dark Zagi in the final episode, she appeared in Komon's memories to congratulate him.
Powers and Weapons
- Unlike the other Deunamists and Dark Ultra Hosts, Riko demonstrated no physical or mental superhuman abilities nor a transformation item/weapon. However, as Dark Faust's host, she showed remarkable stamina as she shared her injuries and healed very quickly between battles.
- Her actress, Shion Nakamaru also appeared in Ultra Galaxy Mega Monster Battle: Never Ending Odyssey as Commander Harlan the leader of the Alien Pedan Reionics Hunters and Dail's superior. She also appeared in Ultraman Saga at the end as Takeru's mother.
- Just like Yuko Minami, Beth O'Brian and Julie, she is the female host of an Ultra but is the second to share genders after Beth and is the first one whose counterpart is a Dark Ultra.
- She gave Komon the bird-like keychain that he uses as his amulet. The amulet would later be what saved him from Mizorogi's attempts to control him and breaking him out of his depression.
- As revealed in episode 32, Riko was grouped with the Deunamists alongside Hiroyuki Misawa. This hinted the fact that Riko is similar to Mizorogi, being potential candidates of Nexus' host but turned into an expendable for the Unknown's plan to come into fruition.