Nagi is a bounty hunter with a fierce reputation who has lost but one target in her distinguished career — the space pirate Ryōko — and wishes to wipe that blemish off an otherwise perfect record.

Traveling with her cabbit Ken-Ohki, Nagi makes a living hunting down wanted criminals in the galaxy. So far, she has only one quarry to have eluded her - Ryōko. She had tracked the space pirate to Earth, where she had taken Tenchi Masaki hostage, thinking he and Ryōko were lovers.

Originally, the two were to fight in space, but a complication occurred, Ken-Ohki and Ryō-Ohki had fallen in love and would not fire upon each other. So a "wild west" setting was created by Washū on the planet Venus so that the two would fight it out. It ended with Ryōko about to kill Nagi, but the cabbits intervened; Ken-Ohki threatening to fight and Ryō-Ohki begging her to spare Nagi. So Ryōko released the bounty hunter.

From time-to-time, Nagi and Ryōko would cross paths during the time the Masaki clan would be pursued by the Jurai Military and the Galaxy Police. First, the Masaki clan had ran a bar on a resort planet to get needed money. Nagi had walked into the bar to get a drink, but stormed out when she got the overpriced bill. When the Masakis had to leave the bar in a hurry, Nagi was on their tail, but was impeded by G.P. cruisers. At another time, Nagi entered a bathing-suit contest just to spite Ryōko and won, only to have Ryōko steal the prize money.

However, the last time they met, Nagi helped out her old rival when Tenchi, along with the knights Azaka and Kamidake, went to Jurai to rescue Ayeka, who had been kidnapped by the false emperor Kagato. The main reason why she chose to help the group was that she didn't want anyone else to take Ryōko's life. Nagi even passed up a chance to fight Ryōko, as Ryōko was badly injured from her previous fight against Kagato, and Nagi preferred not to take advantage of a wounded opponent. At the end of the series, she and Ken-Ohki were still searching for Ryōko, who had disappeared after the battle. Though she has protected Ryōko and wished for her safety, Nagi professes that they're not friends, and that she hunts her only to settle their unfinished business.

Unlike Ryōko, Nagi does not have any superhuman abilities. She instead relies on advanced technology, such as an energy sword and whip, and her excellent fighting skills to compensate for Ryōko's sheer power.

(source: Wikipedia)