While out shopping for her mother, Meimi is almost hit by a truck and falls off her bike next to a pet store. A hedgehog for sale giggles at her, causing Meimi to become irritated. Later, however, when asked to watch the pet store, Meimi notices that all the other pets have a friend or family to keep them company, except the hedgehog, and she starts to feel bad for her. The pet store owner suggests that Meimi asks her parents if she can have the hedgehog, and he promises to save her for Meimi until she comes back.
Unfortunately, while Meimi is gone, a man offers a large amount of money for the hedgehog, who Meimi has decided to name Ruby, and the store owner breaks his promise to wait for her. Meimi was able to get her parents to agree by making them
reminisce about their engagement ring, but she goes back to the store to find Ruby is gone.Meimi promises herself to not feel too sad and hope that Ruby has found a good home, but while Seira is explaining her next mission, Meimi breaks down in tears. Saint Tail needs to steal a diamond, known as the Polar Tear, back from a brother who decided to keep it, although it was only half his. When Meimi goes to find the Polar Tear, she's shocked to find the man, who bought Ruby fed the diamond to her so he could blame his brother for losing it.
Saint Tail snatches Ruby and takes off, leaving Asuka Jr. baffled as to why she would steal a hedgehog. While chasing after her, Saint Tail slips and Ruby falls on Asuka Jr.'s head. Saint Tail yells to him, telling him to give her the hedgehog. Asuka Jr. demands to know what the big deal is with the hedgehog, when she was supposed to be stealing a diamond.
Saint Tail is able to get Ruby back and escape with her, but she feels guilty for not giving Asuka Jr. an explanation, so she goes back to do so. Ruby's nose is tickled by a bit of Saint tail's confetti, and she sneezes, the Polar Tear shooting out her mouth. Saint Tail leaves the diamond for Asuka Jr. and the police to deal with and happily takes Ruby home to be her pet.