Kotone and her Onii-chan came home from shopping one day when she noticed a white baby seal, spotted with coffee stains, atop a neighbor's garbage. In usual Kotone-fashion, she convinced her brother to let her take the seal home with them. About a week later, A flyer described a lost white seal -- the picture on it was the same as the seal Kotone found before. Goma-chan's owner is a boy named Alex, and with Goma-chan's 'mediation,' the Kotone and Alex became friends.
Goma-chan is actually the mascot of "Shounen Ashibe." Also, Goma-chan's introduction was based off an actual event. (by Kayori-kun)