Gu-Gu Ganmo

One morning in the Tsukuda household, Hanpeita's sister, Tsukune, lets his pet bird escape out of spite. On the way home from school, she finds a strange egg from another planet and brings it home to give her brother, in order to make up for her earlier mistake. However, he isn't too pleased with it. Not too long after, the egg swells up, cracks its shell, and out comes a pink...