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.
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.
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.
Initially depressed, and saddened by her father's death, Mika was overlooked, and thus became a bit of a recluse. After Yusuke Godai cheered her up, she became a more active member of the team, helping them with Gurongi research, and looking into Kuuga's belt to help, becoming more cheerful, similar to Godai.
After the Arcle Prototype was fused with her spine, she gains the ability to transforms into a Kamen Rider Kuuga.
- Rider Height: 190cm
- Rider Weight: 90kg
- Ability Perimeters:
- Punching Power: 1 ton
- Kicking Power: 10 tons
- Max Jump Height: 10m
- Maximum Running Speed: 100m/7.2s
Growing Form (グローイングフォーム Gurōingu Fōmu) or so rumored as White Warrior by the internet is the weakest form of Kuuga and has white armor with small horns. Unlike Yusuke's Growing Form, she can alter any material into a cannon-like weapon. Although her power is weak in this form, she can still use the finisher called "Growing Kick" (グローイングキック Gurōingu Kikku), though it is only 1/3 as strong as the Mighty Kick.
- Rider Height: 200cm
- Rider Weight: 150kg
- Ability Perimeters
- Punching Power: 80 tons
- Kicking Power: 100 tons
- Max Jump Height: 50m
- Maximum Running Speed: 100m/2s
Similar to Kuuga's Ultimate Form, the black form's eyes flashes between red and black, then completely black when she loses control to it. Her most dangerous form, Ultimate Form (アルティメットフォーム Arutimetto Fōmu) or rumored as Black Warrior in the internet, combines all the powers of the other forms, Ultimate Kuuga has a much different design colored black with gold (and a little silver) trims all over her body, as well as having five horns on the head crest, a grey belt core and spiky-looking armor.
- Mika is the only female version of Kuuga.