Kouhai's Adventures of Tokyo Mew Mew was the first ever Kouhai's Adventures story. Written by InukaneYumiko under the pseudonym Bunnytown42, the web novella released its first chapter on August 19, 2014. Kouhai's Adventures of Tokyo Mew Mew crossed Double Date (Rhythm Heaven Fever) and Tokyo Mew Mew, along with other various franchises.
On the ride home from school, Kouhai (the male student from Double Date) is bathed in a strange orange light and sees himself being merged with an Arctic Fox. At school the next day, he displays several fox-like behaviors, such as barking and eating eggs fresh out of the chicken. That afternoon, he sees a fifteen-foot squirrel who wants to attack him. A strange Goth named Ryou Shirogane tosses a pendant at Kouhai, and he transforms into a cross-dressed fox-boy named Mew Kouhai. Kouhai uses his newfound fox-like powers to attack to squirrel, but loses the battle and is knocked unconscious.
Kouhai awakens in the basement of the newly built Mew Mew Café, where Ryou and his assistant, Keiichiro Akasaka, tell him that he is a "Mew Mew", a human infused with endangered animal DNA to fight parasitic aliens from Venus. His first task as a Mew Mew is supposed to be finding the other 41 Mew Mews, but instead of helping the men, Kouhai decides to do what a good boy should do and find his family. Unfortunately, he isn't in the Mew Mew Café in Tokyo, but another branch in Mexico.
On his way home, Kouhai battles parasite-infused animals, meets humanoid aliens, and finds the other Mew Mews, the first being Dora the Explorer (infused with lizard DNA). He is also embarrassed about being seen in public in his girl panties, bra, and skirt that come with his "Mew Mew Kouhai Metamorphosis", or transformation into a fox-boy.
- Kouhai is the main character of Kouhai's Adventures of Tokyo Mew Mew. He is quite timid when it comes to trying new things, and tends to keep quiet whenever he can. However, he isn't afraid to lash out at people he gets angry with. He is the first Mew Mew found by Ryou and Keiichiro, but not the Mew Mews' leader (because of this, his attacks aren't all that powerful). On a ride in the car, Kouhai was infused with the DNA of an Arctic Fox. His transformation color is orange.
- Ryou Shirogane is the only son of the two scientists who started Project Mew Mew to combat invaders from Venus. When his parents died due to a major attack from an extremely powerful fossil infused with an alien parasite, Ryou continued and finished the project. He isn't a Mew Mew, but to test the safety of the DNA injections, he fused himself with Irimote Wildcat DNA. However, since his DNA wasn't a great match for the cat DNA, it only gave him the ability to turn into a kitten for 20 minutes. If he stays in kitten form longer than that, he will not be able to turn back into a human. Also, if he says his transformation trigger phrase, "Mew Mew Ryou Metamorphosis", the DNA complications will cause him to literally explode.
- Keiichiro Akasaka is Ryou's assistant, who is constantly pursuing a girl to be his "future husband". Other than that, he does almost nothing else to help the Mew Mews and Ryou.
- Dora the Explorer is the second Mew Mew, who is found in Mexico by Kouhai. She is very loud, bilingual, and unafraid to help and annoy her friends.