Justin is an orphan who was seemingly abandoned as a baby. For the first few years of his childhood, he lives in an ill-conditioned orphanage where he's abused and forced into child labor, but remains a kind and cheerful child the best way he can. One day he runs into Natsu, a clever and mischievous pick-pocket who has big dreams and hidden heart of gold. As Natsu is fleeing from the police, Justin hides him and fools the authorities which impresses Natsu, and upon seeing the boy's living conditions, he offers him a place in his gang which he accepts.

In Natsu's gang there's Lucy a former prostitute who was left destitute by her father's death but is one of the most noble and caring individuals there is, Sting a loose cannon, escappe from an asylum who serves as the gang's muscle, and his brother Rogue the cool headed brains of the operation. Together they use their wit and street smarts to get by, and someday have a better life. They welcome Justin into their group and make him apart of their schemes, though Lucy is strongly against the idea.

Justin is not a natural at living on the streets, his first time helping the gang, he almost gets caught but is saved by another streetwise urchin. Gray, a laid-back, charming, but very moral former member of Natsu's gang who warns Justin that while a life of rebellion and crime is fun, it'll never be enough and that he should try to live life honestly while he's still innocent. Justin doesn't understand and he later learns that Natsu is still very bitter over Gray leaving, under the belief that Gray thought he was too good for the group, and tells Justin to stay away from him. Despite this, Justin secretly visits Gray to let him teach him out to stay out of trouble, revealing he's been on the streets longer than anyone in the gang.

Over time Justin learns to be just as streetwise as the others and the gang treats him like family. He grows to bond with all of them especially Natsu and Lucy. However, he eventually realizes that although he enjoys being with the gang, he feels something is missing.

Meanwhile in Park Avenue, Juvia is a kind, pious, and gentle young woman who's just returned from boarding school to move in with her brother Jellal, a gentleman of wealth and his loving wife Erza. Though Jellal and Erza are always loving toward Juvia, Jellal has become obsessed with work and trying to cure Erza who has become so ill with grief over an awful tragedy, that she cannot even leave her bed. Because of this Juvia is often left by herself in the house and feels very lonely, having unable to make friends in boarding school.

But fate steps in when one winter's night when Natsu's gang are jumped by the goons of a notorious crime lord, Justin is taken for ransom but he manages to escape. Beaten up and sock from the cold, he passes out on the door-step of Juvia's house. She brings him inside and nurses him back to health, then offers to let him live with her upon learning he's an orphan. Believing Natsu and the others to be dead, Justin accepts.

Under her care, Justin attends school, learns the importance of honest work, and feels a familiar connection with Juvia and even more familiar one with her brother. Gray also checks in on Justin occasionally leads to a romance developing between him and Juvia.

But in this city, the mysterious crime lord is the one who makes the rules and he has plans for both of Justin's families. Can this little boy protect the home and loved ones he's spent so many years searching for? And will he ever know his birth parents?