Minagi's name is taken from the Minagi railway station in Japan.
Minagi looks almost exactly like Ryoko (with the exception of two crescent-shaped scars across her cheeks), and for good reason - from a genetic standpoint she could be considered the space pirate's daughter. However, she considers herself more a younger sister than anything else. Minagi was created artificially when Yakage, an apprentice of Washu, stole a sample of Ryoko's DNA and spliced it with his own. While similar in both appearance and abilities to her "mother", the two couldn't be any more different in personality: Minagi is highly enthusiastic, polite to a fault, and shows no interest in alcohol. They do share one important quality, however; both women are devoted to those they love unto death.
She acts as Yakage's protegé and servant, confronting Tenchi and the others shortly after their battle with Kagato at her master's behest. She suffers from amnesia after a tussle with Ryoko as a result, but while recouperating befriends the entire group. She and Sasami share a particularly close bond. Minagi regains her memory while fighting Yakage, wanting to keep her newfound friends out of danger and remember her past. While very hurt she doesn't mind dying at her master's hand, pleased to have done what she could to help her father create the perfect sword (unknowingly, one Yakage meant for Minagi to wield).
She survives the encounter, and now decides to follow in Ryoko's footsteps as a space pirate while still living by Yakage's teachings. However, her activities are more akin to the stories of Zorro or Robin Hood than to Ryoko's former career, targeting "bad cargo ships and government officers" (sic).
Unfortunately, Minagi is still often mistaken for her notorious sister, with a case of mistaken identity with Asahi Takebe getting her involved in an issue with Yume and the Shima Brothers. Yakage had come into possession of one of the three Hielzen-S swords ("Kageba, the Shadow Blade"), but the sword was taken from him by Hishima, who had threatened Minagi's life lest it was handed over. Upon trying to retrieve it, the current owner Yume was unsympathetic to the past wishes of a dead man, ordering Hishima to dissuade Minagi by force. Though she survived the incident she is severely hurt trying to save Asahi's ship, but is well enough to recover under Washu's care (with the generous "donations" of blood and marrow from Ryoko helping matters further).
Minagi later captures an animal smuggler who was en route to deliver a Mitsu, and also helps the gang remember Washu, who under the orders of the Dr. Clay controlled Dark Washu had sealed their memories of her to cause her distress. Following Ryo-ohki's signal to Europa, they eventually confront Dark Washu together, and after Washu defeats her robot copy, the missing left eye of Clay that acted as his back-up breaks away, only to be destroyed by Minagi for the harm its caused her friends.
Clones of Ryoko have popped up several times in Tenchi Muyo! animation and literature over the years. The original OVA series Tenchi Muyo! Ryo-Ohki later used the concept for Zero. In 1997, an American comic published by Pioneer wrote of a more sinister offshoot named "Inferno".