Hayami is an attractive and charming man that most of the students, parents, and faculty of AGHS fall for (save for Chuta Ohsugi). He however, has ulterior motives, much like fellow Horoscope Sarina Sonoda. After she is defeated by Kamen Rider Fourze, Hayami takes over (albeit reluctantly) her duties as dispenser of Zodiarts Switches. True to the nature of his Zodiarts, which is based on a star sign that takes the form of a scale, he has a habit of using terms related to weight like "light" and "heavy" when talking to others.
Unlike Ms. Sonoda, who would distribute her switches to any distressed, emotional or vengeful students, Hayami decides to go directly after those who have the potential to become Horoscopes in the hopes to increase their ranks, more so after gaining his Eye of Laplace ability.
Hayami first appears in episode 13 and briefly change into Zodiarts form in episode 14 to saves the unconscious Ms. Sonoda while casting an illusion over her to protect her identity from Kamen Rider Fourze. Hayami now takes her duties to distribute the switch. Unlike Sarina Sonoda, who would distribute her Switches to any distressed, emotional or vengeful students, Hayami decides to be more picky with his choice of target students and only goes directly after those among his prized pupils who have the potential to become Horoscopes in the hopes to increase their ranks. After the defeat of the Dragon Zodiarts and Sonoda's banishment to the Dark Nebula, Gamou tells Hayami to speed up his recruitment stategy.
He had accidentally brought Natsuji Kijima, the Cancer Zodiarts, into the Horoscopes' ranks. Not liking the turn events, Hayami's dislike towards Kijima is further aggravated by the newcomer's blatant disrespect towards him on many levels. After Kijima is defeated by Kamen Rider Meteor, Hayami takes advantage to get rid of Kijima. Hayami takes the Cancer Switch that Kijima accidentally dropped, then disguised him in the form of a meddling detective. Hayami then tells Virgo to banish Kijima or their identity will be exposed. After banishing Kijima, Hayami was proud of himself in manipulating Virgo to get rid of Kijima.
Though Gamou suspects Hayami's scheming, he allows him to do as he pleases if it suits their goal. Gamou then sent Hayami to Kyoto to destroy the fours altars of Cosmic Energy that is sustaning The Hole over Kyoto, all so that AGHS becomes the only place with one such vortex where Cosmic Energy flows into. To that end, Kamen Rider Fourze's presence is needed, which is why the field trip is changed to Kyoto in the first place by Gamou. Gamou also sent Kou Tatsugami, the Leo Zodiarts, to watch Hayami's progress on the job. While the three altars are destroyed and Leo Zodiarts had defeated Meteor, Libra confronts Fourze.
After having been sent into space by Fourze's Cosmic States Rider Super Galaxy finish, before the final attack could finish him, Virgo transports him back, and at the same time Libra use his khakkara Dike to destroy the last altar. Back at he Horoscopes lair, Gamou tells Hayami that he is of no further use and tells Virgo to banish him to the Dark Nebula. Before being sent to the Dark Nebula, Libra's desperation to not be sent to the Dark Nebula manifests his Supernova powers, the Eye of Laplace. Seeing Gamou's sign as Sagittarius, Gamou delays his banishment in order to find the other Horoscopes members.
Hayami is the one who recruits the Capricorn, Aquarius, and Taurus Zodiarts. During Virgo's betrayal arc, even though Hayami and Tatsugami had a bad relationship, the two team up to kill Virgo. Hayami then mocks Virgo, as he is the one that survives.
As of late, Hayami begins to question Gamo about the Horoscopes's goal, more so during the Gemini Zodiarts incident, when he begins to question if Gamou wants him or his Horoscopes Switch. Upon learning the nature of the Day of Awakening, Hayami resolved to find the final Horoscopes member who would become the Pisces Zodiarts. But interviewing Taira Katagiri of the glee club, the swim club's best member, Chosuke Ban the delinquent, a pop idol, and a former fan of Cygnus, Hayami's search goes to no avail with Tatsugami attacking him for each blunder. However, the last person on his list was Ran Kuroki.
Once confirming Ran to be the final Horoscopes member, Hayami formulates a scheme to make it seem that he betrayed Gamou to protect Ran, giving his Libra Switch to the Kamen Rider Club as a proof of his conviction before it ended up with Tatsugami who secretly gave it back to him as Ran ends up becoming the Pisces Zodiarts to protect him. Once everything goes to plan, Hayami reveals his true colors before taking a Rider Super Galaxy Finish meant for Sagittarius. Drifting into the Dark Nebula, Kouhei Hayami is vaporized by the the vortex's lightning, killing him.
Video Game appearances
All Kamen Rider: Rider Generation 2
The Libra Zodiarts appears as a monster in the video game All Kamen Rider: Rider Generation 2.
Kamen Rider Travelers Record
The Libra Zodiarts appears in the video game Kamen Rider Travelers Record.
Hayami has a Ph.D in physics, which puts him in a good position to be the principal. He is able to calm an entire crowd of worried and protective mothers, who have heard things about the Zodiarts attacks.
As the Libra Zodiarts, Hayami wields a khakkara called the Dike as his weapon to create illusions, fool his targets, and can copy Kamen Rider Fourze's powers to assume a doppelganger form known as "Fake Kamen Rider Fourze Base States", as well as brainwashing the victim, such as the Perseus Zodiarts. He demonstrated his illusion abilities by making an unconscious Sonada have the appearance of Gentaro Kisaragi to throw off Kamen Rider Fourze (who is Gentaro). The khakkara can also be used, even from an incredible distance away from Dike, as he destroyed the last alter in Kyoto while he was in space, simply by channeling his power through the khakkara.
After being defeated by Fourze, Gamou decided he was useless, and it was time to send him to the Dark Nebula. Hayami was so desperate to not be sent to the Dark Nebula, that he manifested his Supernova ability, which is the Eye of Laplace, which allows him to see who has the potential to be a Horoscope. Gamou, upon Hayami learning him being the Sagittarius Zodiarts, delays his trip to the Dark Nebula, letting him stay on Earth to find other potential Horoscopes' members.
- Height: 200 cm.
- Weight: 95 kg.
- Rider Stats
- Punching Power: 2.5 tons
- Kicking Power: 6.3 tons
- Highest Jump: 20 m.
- Fastest Speed: 100 m. per 6.2 seconds
The form he assume by using Libra Zodiarts' power. Unlike Fourze, he lacks the ability to use the powers of the Astroswitches
His given name is also the Japanese word for "fairness", "impartial", and "justice", referencing that the constellation of Libra represents the scales of Astraea, the Greek goddess of justice.
- Hayami is played by Kousei Amano, who previously played Sakuya Tachibana in Kamen Rider Blade.
- This is referenced in the self parodic Super Hero Taihen, a set of net movies for Super Hero Taisen, wherein it is "revealed" that Hayami is actually Tachibana.
- This happen again in Fourze's Net Movie when Gentaro mistaken Garren as Hayami.
- While other Horoscopes wear the same designed robe, his and Leo's robe had their own special design.