San-X Frog (Kerori) is either white or green depends on his mood. When he's feeling sad or depressed, Kerori is green. But the next day, he always feels much better, and he changes back to white! The little Tadpole is a nice companion for Kerori, so is the Blue Worm. The Blue Worm comes to Kerori when he's sad. What a buddy is for, right?