A young golden hamster
character created by Sanrio
Also called simply "Kuririn," the little male hamster was born February 4. His hat is made from an upside-down flower, and his favorite foods are cookies and sunflower seeds. While hamsters are naturally timid, Kuririn manages to stay laid-back, curious, and spunky. His talents include speed-nibbling and burrowing, and he enjoys playing hide and seek with his girlfriend Sakura. The pair also enjoy exploring for buttons, seeds, and anything else Kuririn can hide in his tissue paper bed.
First introduced in 1998, KoroKoroKuririn products are readily available in both Japan and the United States. He is frequently depicted with Sakura, and the two of them are commonly shown eating or frolicking.
I have sometimes seen the name spelled CoroCoroKuririn, but it is spelled KoroKoroKuririn at sanrio.co.jp - sanrio.com uses only the Kuririn form - so I am considering that the official spelling.
Unrelated to Kuru Kuru Kururin, which is a video game.