Karin Kokubu is late for school one day when she comes across an apparently injured yellow pig. It turns out the pig wasn't injured, just hungry, and he gets back his health when he eats Karin's apple. When Karin gets to school, she discovers that the pig has stowed away in her backpack, which causes her more trouble. Later she meets the pig again and finds out he can talk and fly, and he gives her a "pigompact," which she opens--and a pig snout appears from it and attaches itself to her nose! She finds the pig again, who explains that he is actually Prince Tonrariāno III of the planet Buuringo. He tells her how she can transform: by saying "BA BI BU BE BOorin!" and she transforms into a superpowered pink piglet called Buurin. This is not something Karin is happy about at all, as she'd rather transform into a heroine like her idol the henshin hero tokusatsu character "Cutey Chao" (who is possibly a reference to Cutey Honey). Tonrariāno (who she calls Ton-chan) tells her if she can collect 108 pearls by doing good deeds as Buurin, she can do so.