His only appearance was made in "Nana's Invitation", where Cooku was jealous and cross of Tayo and the other buses, because he was talking to Nana most of the time. When Hana told him that Tayo and his gang are going to see the fireflies, he was worried that they might get hurt. When Cooku invites Ractor & Champ to come to the rescue, he tells Hana that he has a spare tyre on his back after Ractor pulls him. Later, Tayo and Cooku became friends.
- He is voiced by Erik Athavale in the English version (season 2). His voice sounds like Shine's.
- In Cooku & Champ's Trip To The City, his new voice sounds more feminine and gains a country accent/sounds like a cowgirl.
- His original name was Coco.
- Paul Panting was originally going to play Cooku in the US version but dropped out. Kate Higgins voiced Cooku instead.
- Paul Panting still plays Cooku in the UK version.