Tsukimi 月見, the moon-viewing, is a festival related to the moon phases, which takes place on the 15th night of the 8th month, calculated by the traditional Japanese lunisolar calendar. By the modern calendar, it usually fall on the mid/end September or at the beginning of October.
The Buddhist story tells that on a day of Uposatha, an old man asked for food from a monkey, an otter, a jackal and a rabbit. The monkey collected fruits and offered them to the old man, the otter brought him a fish and the jackal a lizard. The rabbit didn’t have anything to bring, because the herbs constituting his food weren’t good for humans. Then, the rabbit decided to offer his own body and jumped into fire. But, surprisingly, his body did not burned, because the old man was Sakra. And for people to remember the rabbit’s sacrifice, the old man drew the rabbit’s image over the moon.