His full name is Rei de Richard (レイ・ド・リシャール Rei do Rishāru). In the anime, his partner is Asahi.
His voice actress is Mutsumi Tamura.
Rei is a white plush kitten. He has a blue hair tuft and a long tail with a bit of pale purple at its end. He wears a light blue collar with a purple bow, as well as a yellow ring with a star around his right leg. Like the main kittens, he has pink star-shaped paw pads and a yellow star in his left ear.
Rei calls himself "a prince of a royal family from the country of love".
Asahi Minamikawa: Asahi is Rei's partner.
Yuni: Yuni is Rei and co.'s rival.
Similar to Mew, Rei fell from the sky before meeting his human partner.
- Rei knows some French words as shown in Episode 20.