Rei Form - Human Form
Name Kou
Race Rei
Birthday January 17
Age 25
Gender Male
Height 184 cm (6'0)
Weight 70 kg (154 lbs)
Blood Type B
Affiliation Ryuko (Creator and King)
First Appearance
Manga Debut Volume 4: Chapter 16
Anime Debut Episode 13
Seiyū Katsuyuki Konishi

Kou (洸 Kō) is a Rei who helps Akira in his to preserve the balance between the Shadow and Light.


A 25-year-old man. Kou has various piercings on his ears and wears wire frame glasses. Messy black hair tops his head. He has purple eyes but they become a gold color with an almost cat-like slit when he goes into his Rei form. In the manga, Kou can also transform into a big white wolf with two black markings either side of his body.



Ryuko and Rei/Wolf form Kou.

Kou generally gives off a cheerful vibe, coming off as a perverted, happy-go-lucky individual who enjoys flirting with almost anyone he meets, particularly Aya and Haruka. However, he is actually tormented by the guilt of having fled from the battle and abandoned Ryuko, leading to the latter's death. As such, he is determined to protect Akira no matter what, even at the cost of his own life. As such, despite his mistake of the past, he is in fact staunchly loyal to his comrades, Akira in particular, and will not hesitate to lay down his life for them. Though outwardly playful, he can be serious when the occasion calls for it, and is surprisingly knowledgeable and detail-oriented, serving as a source of console and reassurance.


One of the Rei, and a perverted 25-year-old friend to both Akira and Kengo from an event that occurred several years ago. They call him 'Kou-nii' in anime while Haruka calls him 'Onii-chan' as Kou insists. Loyal to Ryuko, and is one of Ryuko's five "children" in the manga. In the manga, he has an ability to drain darkness out from others' bodies with his unusually long canine teeth, an ability he has exhibited twice (once off screen) in order to return Kengo back to normal. He resembles a vampire when doing so. He has straps all over his body that serve to restrict his power. He also has a scar under his left eye; he gained it 2 years before the Monochrome Factor story (manga) while fighting a berserk Kengo who had absorbed too much darkness.
Kou vs Kengo

Kou vs. Berserk Kengo


Powers and AbilitiesEdit

Rei - A being of light, Kou's capabilities surpass human and he does not age physically.

Weapon - In his Rei form, Kou uses his claws and fangs, he can even transform into a wolf-like Rei. Also uses straps for binding his opponents.

Magic/Spells - He knows a few tricks as he made heavy seals to conceal Kengo's dark factor to make sure Kengo doesn't absorb anymore darkness or go berserk again. He was also was able to make Akira fall asleep by placing his hand in front of Akira's face.



  • Kou's character song "Dive" is sung by his Seiyuu; Katsuyuki Konishi.