Taro arrives as an infant, discovered by an elderly couple after they shelter a mysterious traveler on New Year's Eve. This traveler, revealed as the New Year God, directs the woman to draw water at dawn from a spring on Mount Dodo to fulfill her wish for a child. Finding Taro the next morning confirms the traveler's divinity and his link to the child.

Raised by the couple, Taro grows into an active, courageous twelve-year-old. He repeatedly defies village edicts forbidding approach to Mount Dodo, driven by curiosity about the "mountain demon" blamed for the volcano's eruptions. During one forbidden excursion, he uncovers the true cause: a weakened firebird trapped within the mountain. Each of its failed escape attempts inadvertently triggers volcanic activity. Compelled by compassion, Taro vows to help the creature.

Seeking divine aid, Taro summons his patron god. The same traveler who brought him reappears, now clearly the New Year God, astride a white horse with a golden mane. The god reveals only the "Water of Life" can heal the firebird and tasks Taro with retrieving it, launching the boy on a perilous journey beyond his village.

Taro's quest demands confronting supernatural entities, including an evil snake that stole the Water of Life. This snake wields the power to revive itself using the stolen water, presenting a relentless foe. Taro demonstrates resourcefulness and bravery throughout, cooperating with creatures and deities encountered to overcome obstacles. His goal extends beyond healing the firebird; he strives to secure the Water of Life to bring happiness to his entire village.