Coco is protective of her older, but not more mature, brother. Her first appearance indicated that she is a bit bossy and believes in honoring one's promises. She loves her brother very much and shows that she wants him to always be happy. Like her brother, she also carries and uses a strange yellow dolphin-shaped water pistol and uses it to temporarily control people. She mainly uses this tool to make Yuki comply to her demands.
Coco's appearance is much more unusual and alien than her brother's. She has pinkish eyes, similar to Haru's purple ones, and she wears large glasses with thin rims. Her hair is pink with turquoise and yellow flower designs in it. She wears a large blue and gray collar, a black bikini top, a large gray and blue polka-dot skirt, a blue backpack with pink straps, gray sleeves, and gray high-heeled boots.
- Coco is the only alien in the series who never tries to look like a regular human.
- In a Q&A session on Twitter it was confirmed that Coco's glasses are prescription glasses.
- In another session it was stated that Coco's skirt can actually store items. That aspect ended up unused in the anime.
- Apparently Haru and Coco never fight because whenever Coco gets angry, Haru still smiles.
- She is an E cup. Her three sizes from the top are 89.60.91.