[henshinzero]

Real Name: Gamou Hikaru/Zero
Rider Name: Kamen Rider Constellar
Motif: Alien/Ophiuchus/Constellations, Supernova States (Alien/Ophiuchus/Zodiac)
Series: KR Fourze
Theme based on: Constellations
Rider Power Source: Zodiarts/Horoscopes
Arsenal:
- Belt: Constellar Belt (almost like Agito)
- Henshin Pose: Clicks the switch to summon the belt from his waist and inserts it on the belt. It first shows his horoscopes self then his rider form.
- Forms: Constellar Ophiuchus, Constellar Supernova
- Weapons: Ophiuchus Sword
- Motorbike: Auriga
- Rider Items: Zodiarts Switches (Constellar Switch & Supernova Switch)
- Finishers: Constellar Combo Breaker
Allies: None, KR Club (later on)
Kaijin: Zodiarts

Story:
Gamou Hikaru trained under his grandfather, Gamou Mitsuaki at an early age.

He is anti-social like Kengo. Hikaru hides his real name in secret as Zero, meaning he has no heart to make friends with anyone and considering himself the loner. Zero dislikes Gentaro when he came into the school, and sees him as an annoyance. When Kisaragi became Fourze, he became more ticked that it should've been Kengo to be the one for him to fight instead.

Serving under the Horoscopes & his grandfather, he helps him with the mission, but later he gets betrayed. Kisaragi's words of friendship start to sink in a little to Zero inspiring him to fight the zodiarts, even though he became the Ophiuchus Zodiarts as he got to the age of a teenager. Zero acts like an adult but sometimes he learns you gotta act like a real teen and let go. He doesn't become an official member of the KRC, but acts as an informant to the group of zodiarts activity. Plus he has the ability to sense zodiarts from the stars.

(This kind of rider should've been the secondary rider and Meteor as the 3rd instead)