Kochu has magenta hair and eyes, with a similar face and body type to Kaiba. She has a widow's peak and her hair seems to be formed somewhat like a ponytail, with the end curling into a long spiral.
She wears a ragged, muted green shirt with long sleeves and long dark pants. Her shoes also have holes in them.
According to Kochu, her past is filled with "unhappy memories" and several ex-boyfriends. She wanted to leave these behind and start a new life with her boyfriend Butter.
Although not much else of her backstory is revealed, it's heavily implied that she's poor with her clothing and her cheerful attitude despite having to stowaway while her boyfriend has a ticket.
Kochu is seemingly carefree and cheerful in her interactions with others. She's quite friendly to strangers, talking frequently to Kaiba (in Kaba's body) and Hyohyo throughout the episode despite the pair's inability to speak. Kochu mentions her unhappy past several times in conversation but always follows these statements with a positive outlook on her future.
However, Kochu is far from spineless. When she discovers her boyfriend has been using her to smuggle memory chips and evidence that he might be cheating on her, she immediately confronts him. She's shown to be aggressive when upset, even physically fighting with Lum when insulted.
Kochu meets Kaiba and Hyohyo in the luggage room. She explains that she snuck into the baggage as she and her boyfriend didn't have enough money to buy two tickets. She goes to visit her boyfriend, and Kaiba and Hyohyo explore the luggage deck.
Upon Kaiba and Hyohyo's return, Kochu introduces them to her boyfriend, Butter.
Later while trying to find her favorite pair of underwear, Kochu discovers that her boyfriend has been using her to smuggle memories chips.
Kochu confronts Butter at the door of his room, throwing the smuggled memory chips in his face. Butter scrambles to pick them up and hide them before someone sees him. Kochu however, is more concerned about the stockings she found in her belongings that don't belong to her, sure of Butter's infidelity. Butter pleads with her not to enter his room. A large crowd begins to form.
Lum leaves Butter's room at the commotion, asking who Kochu is. While Lum and Kochu begin to fight, Butter tries to crawl away. But their brawling causes hundreds of smuggled memory chips to fly into the air, along with a number of pairs of underwear.
Vanilla begins to interrogate Butter about the chips before announcing to the people that transporting memories is a serious felony. He demands to see tickets of Butter and the two women. At Kochu's refusal, he says that stowaways are to be executed, bringing out his blasting gun.
To Kochu's bitter shock, both Lum and Butter reveal their tickets. Lum runs and then falls on her face, with her ticket dropped onto the floor. Vanilla attempts to convince Butter to confess to his crime and bribe him in order to let everyone go peacefully. Butter confesses to convincing Kochu to stowaway in the ship. Before Vanilla can react, two women from the crowd jump in to protect Butter, with their tickets on display. They plead and beg with Vanilla to instead shoot Kochu.
Vanilla shoots Butter and then Kochu, then expresses remorse for a short second at the reveal that neither of them had converted their memories into chips.
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