Pinocchio, also known as Mokku in the Japanese version, begins existence as a wooden marionette. Carved by the elderly Geppetto from an oak branch felled in a storm, the puppet is granted life by the Oak Tree Fairy in response to Geppetto's wish for a child. He remains wooden, requiring moral development to become human. His design includes blue hair, painted cheeks, light purple eye shadow, and a cylindrical brown-red nose, with jointed limbs. He wears a red-brown hat with a pale yellow border, a white pelerine, light-blue shorts with yellow buttons, and brown-painted shoes, sometimes carrying a brown or red bag.

As a sentient puppet, Pinocchio exhibits profound character flaws: selfishness, gullibility, naivety, obstinacy, compulsive lying, arrogance, greed, cruelty, and an inability to learn from mistakes. This moral confusion and delinquency repeatedly plunge him into ordeals. He once attempts to murder a human boy with an axe, believing stealing his heart grants humanity. Later, corrupted by wealth after noble adoption, he rides horseback through estates endangering others for amusement. Such actions bring severe punishments, like his nose transforming into a small tree and abandonment in the wilderness.

He endures significant physical and psychological torment—beatings, humiliation, exploitation—often resulting from his disobedience or manipulation by antagonists like the fox Jack, the weasel Willie, and the rat Charlie. His weak neck joint is a vulnerability frequently targeted. Unlike organic beings, he initially lacks senses like smell and pain; magical interventions, such as a ring, grant temporary human sensations, including illness from consuming poisonous berries.

Pinocchio's moral growth occurs gradually through adversity. Early village misadventures involve disregarding advice from his conscience, Cricket, facing consequences. The narrative shifts when kidnapped by the puppeteer Sneeroff, prompting Geppetto's search. During his journey to reunite with his father, Pinocchio encounters supernatural threats like vampires, witches, and a sea monster, increasingly relying on his own resourcefulness. Key events include defending his village from bandits, fostering mutual respect with former bully Franco, and later collaborating with former foes Jack and Willie to thwart Sneeroff.

In the final arc, Pinocchio advocates for sentient trees facing deforestation, drawing military persecution. After Geppetto's arrest, Pinocchio rescues him from Devil's Island, defeating its guardian monster with the Oak Fairy's aid. Stranded with Geppetto and a girl named Gina, he bonds with her as a sibling, helping transform the island into a paradise. Post-rescue, Gina falls ill. Pinocchio seeks healing herbs for her and other afflicted children. His selfless act of curing them culminates in his shooting by soldiers. The Oak Fairy intervenes, resurrecting him as a human boy for demonstrating bravery and kindness, though this severs her ability to guide him further. The series concludes with his transformation affirmed under a symbolic Christmas sky.