Seina's childhood friend, Kiriko Masaki would often be tending to the many injuries that Seina would suffer from his bad luck. She cares for Seina deeply and would fight to protect him from further harm. Even her younger brother Kai would help out Seina in repairing (or otherwise constructing from new) the bicycles that would be wrecked because of Seina’s bad luck.

What was not known about Kiriko was that she actually has blood ties to the Jurai royal family... a small tie, but it exists (she's also older than she appears... she's 33, but looks 21). Even Kai was unaware of their connection and wouldn’t find out until Kiriko’s wedding.

For a time because of this, Kiriko was one of Seto Kamiki Jurai's ladies-in-waiting, and that connection helped Kiriko to gain a position with the Galaxy Police's immigration department, where she worked when she wasn’t on Earth.

It was while Kiriko was working in the G.P.'s immigration department is when she found out that Seina had enrolled in the G.P.. Immedietly, she pleaded to the boy without success for him to leave. Soon afterward, she was assigned to the G.P. Academy, along with Amane Kaunaq. During Seina's training, she had moved into Amane's house at the Academy along with Erma, although it was more to keep an eye on Amane and keep her from making a move on Seina.

It was later on in the series that Kiriko began to feel inadequate compared to the other women in Seina's life – Amane, Ryoko Balta, and more recently Neju Na Melmas. It was after an experiment using Seto's ship Mikagami that her life would be changed. In a ceremony witnessed by Seto's husband Utsutsumi and Emperor Azusa, Kiriko was bonded to a second-generation Jurai tree, thus giving her the name Kiriko Masaki Jurai. The tree's name is Miyuki, and now aided Fuku in powering the Kamidake II, the ship she shared command with Seina and Amane.

Like Amane, Ryoko and Neju, Kiriko was later engaged to wed Seina in a political marriage... and like to the others, was witness to Seina being kidnapped and publicly seduced by Seto’s ladies-in-waiting, who were actually representatives of the Rezma Union who appealed for Jurai's help. As a result, Kiriko, as well as the Rezmans, Amane, Ryoko and Neju, wed Seina and are still assigned to the Kamidake II, possibly the only crew in the G.P. that are all married to their captain.

As a G.P. officer, Kiriko has access to much of the G.P.'s standard complement of weapons and training in their use, as well as her Jurai strength. In one episode, she demonstrated the use of one of these – a bodysuit that featured cloaking technology, which enabled her to attack with complete surprise. Also in the heat of battle, Kiriko tends to concentrate solely on battle and not on the environment around her – which was why when she approached Tarant Shank – covered in the blood of her previous opponents - she became surprised to find that Seina had seen her.

(source: Wikipedia)