Kotone "Kai" Kusakabe

Kotone Kusakabe (日下部 琴音), better known by her nickname of Kai (カイ), is the secondary rider of Kamen Rider Heisei (Ghost), Kamen Rider Larcen.

Past
Like her counterpart, Reika, not much is known about Kai's past. What is known is that she is a ghost stuck in eternal limbo, who collects Eyecons for fun rather than to wish herself back to life. How she got into this situation is unknown, but it is implied that she committed suicide.

Present
"You gotta be faster than that if you wanna get 'em all in time."

- Larcen to Heisei upon revealing she has the W Eyecon Larcen made her presence known to Heisei in a big way when she took the W Ghost Eyecon while Heisei was preoccupied fighting a Ganma. She taunted the purple rider about how slow she was, before using the Eyecon to send a big gust of wind her way and escape. Ever since then, she has developed what she calls a friendly rivalry with Heisei, clashing with her again for the Den-O Eyecon.

Personality
Kai is surprisingly upbeat and cheerful, despite her grim situation and being doomed to forever wander the mortal world. She is happy-go-lucky with hardly any signs of malice towards Heisei, even going so far as to call her "buddy". She seems to steal things just for the fun of it, and would willingly give back the things she stole if it was for the greater good. She states that death has "freed" her from doubts and those who brought her down in the past, implying that she had a tough upbringing with people who used her.

Forms
Also see Legend Rider Eyecons

Larcen's forms are called Damashii (魂 Damashī, Souls), accessed using the Ghost Eyecons. She also bears a headpiece called the Persona (ペルソナ Perusona, Latin for "Mask"), which gives off a glow effect with the rest of her body. The Persona changes with Larcen's numerous Damashii forms, as well as serving as a prefix title for all of the Damashii forms' helms. Differentiating herself from Kamen Riders Ghost, Specter, and Heisei, Larcen normally bears a pair of cracked Wisp Horns (ウィスプホーン Wisupu Hōn?) on her head in most of her Damashii forms, allowing her to use them either for perceiving and sensing Ganma within a 4 km. radius or as a weapon.

By pulling and pushing the Ghost Driver's lever a second time after transforming, Larcen can activate an Omega Drive (オメガドライブ Omega Doraibu) finishing attack tied to the Ghost Eyecon currently being used. If she pulls and pushes the lever four times, she can instead execute an Oomedama (オオメダマŌmedama?, lit. "Giant eyeball" (大目玉?)) special attack.

Devices

 * Ghost Driver - Transformation device
 * Ghost Eyecons - Transformation trinkets

Weapons

 * Gan Gun Arrow - Sidearm weapon

Vehicles

 * Machine Castor - Rider Machine

Trivia

 * The spelling of Castor in terms of the Machine (キャストール) is different to how Castor is usually spelled in Japanese (カストール). This might have been done to make it similar to Cast Off (キャストオフ), implying that the counterpart to Spectre's Houndini form will be Kabuto.
 * Kai, with her cheery and innocent persona, better matches a usual primary rider than a secondary. Likewise, Reika's stoic demeanor evokes the usual secondary.
 * Kai most likely comes from "Kaitou" (phantom thief), which matches up to what she does (stealing things for the fun of it).