Mika Natsume

Mika Natsume (夏目 実加) is the daughter of Professor Natsume, one of Daguva's victims. She was greatly depressed when her father's murder was being overlooked for the Gurongi attacks, taking the findings her father had at their house. But after Yusuke reasoned with her, Mika decides to aid in the Gurongi matter as Jean's assistant. However, she is unable to follow and decides to take up playing the flute her father gave her. But while attending the 12th Arikawa Group Flute Competition, a hostage situation by a disgruntled government worker traumatizes Mika as Yusuke tells her to not to run from her fear and continue. Three months later, Mika is attending a special college.

Novel
10 years after Kuuga's fight with N-Daguva Zeba, Mika found her father's notes about the existence of another Amadam. After sighting a few Gurongi, she goes to the ruins where the prototype Arcle is. She wore the belt and transforms to Kuuga. Similar to Kuuga, her first form is white. The black form's eyes flashes between red and black, then completely black when she loses control to it.

She fights an unnamed Gurongi in her white form, but it's killed by a different one before she can finish it off. Later she fights a jellyfish Gurongi, kills it and is shocked by the explosion she caused. She eventually faces a lion Gurongi, causing her to change from white to black out of rage.

Kuuga (Prototype)
Years after the end of the series, Mika found a prototype Arcle which was created earlier than Kuuga's, but is incomplete because of lack of an Amadam, which causes the user to go berserk. The previous user went crazy and the belt was sealed inside the Coffin of Darkness (Kuuga's Arcle was sealed in the Coffin of Light).

Wearing the belt, she transformed into Kuuga. As the prototype Kuuga, she has two forms, one white and one black. However, she must control both of her powers and temper due to the incomplete Arcle's lack of an Amadam stone, which stabilizes the user.

Forms
After the Arcle Prototype was fused with her spine, she gains the ability to transforms into a Kamen Rider Kuuga.

Trivia

 * Mika is the only Kuuga to be a female Rider.