|Full Name: Karen Mizuki|
|Ranger Designation: Heart Queen|
|Weapons: Magnetic Counter, Heart Cute|
|Power: Heart Cute Magnet Power|
|Vehicle: Heart Buggy|
|Karen is half Japanese and half Caucasian, at eighteen she was a former Japanese Policewoman. She was assigned to investigating illegal narcotics trafficking routes into Japan. During her investigations, Karen uncovered that Crime controlled a majority of these routes and was going to assist ISSIS in destroying these routes. Crime attempted to kill Karen by arranging a fatal car accident, in which the taxi she was in with her father, a fellow police officer, was smashed by a truck. Miraculously, Karen survived the accident but lost her right arm and her father was killed in the process. Enraged and seeking revenge, Karen willingly accepted Joker's offer to undergo his bionic process and join JAKQ to avenge her losses. She fell in love with Gorou towards the end of the series. Her bionic enhancements allowed her to control magnetism. Her magnetic based powers, which she dubbed her Heart Cute Magnet Power, allowed her to attract and repel metallic objects at will. She often used her powers to literally stop bullets in mid-air. Her powers can be further augmented by using her Q-shaped Heart Cute weapon.
Using the Heart Cute, Karen is able to send out waves of magnetic and kinetic energy that can bowl over opponents or force them into erratic behaviors (which she gleefully enjoys and asks afterwards 'Do you want another?'). The Heart Cute can also be used as a blunt impact weapon which she uses to strike opponents. From her right index finger she is able to pull out her Magnetic Counter, which can send out a magnetic detection pulse which she can then use to pinpoint and identify objects, both metal and organic, in a way similar to radar. Karen is a skilled martial artist and is proficient in a number of fighting methods. For a time she was part of the Kono Karate School where she befriended Kono Natsuko who was also a skilled martial artist. Karen has a flair for fashion and often sported tight red leather'hot pants and red long boots.