After Natsu and Happy argue with each other, Lucy finds a six-year-old painting of the guild that depicts Happy as a dragon. She shows the painting to Mirajane, who tells Lucy the story behind it. In a flashback, Natsu discovers what he assumes to be a dragon's egg, and Mirajane's younger sister, Lisanna, helps him care for it. When the egg goes missing one day, Natsu and his friends accuse each other of stealing the egg until it is returned by Elfman, Mirajane and Lisanna's brother, who confesses that he wanted to feel useful by helping them in secret. The egg suddenly hatches into Happy, whose birth breaks the tension within the guild and prompts Natsu to give him his name. Back in the present, as Lucy meets up with a reconciled Happy and Natsu, she realizes that she has never met Lisanna and wonders what became of her.