On a small planet whose inhabitants are made of natural materials, the first Guardians brought a small
Sun and
Moon to bring light to the world and preserve its harmony, traveling in colossal temple-like animals. In the present, despite their differences, the people of the day and night live in peace. However, Necross, a corrupted Guardian of the Sun who previously tried to steal the Sun before being defeated by the warrior Xolal and banished to the Underworld, awaits the opportunity to plunge the world into darkness. In the present day, apprentice Guardians Sohone and Leeyoon prepare to take on the roles of Guardians of the Sun and Moon from Xolal and Yule. On the day of their induction, the light of the Sun accepts Sohone as planned, but the lunar Ewe chooses Mune, a young, inexperienced Faun boy, over Leeyoon. After his imp servant Mox informs him of Xolal's retirement, Necross sees an opportunity to steal the Sun again. After the ceremony, Xolal and Yule teach their respective successors how to operate their Temples before dying, respectively becoming a statue and glowing tree. The following night, Necross sends Pale Snakes to corrupt Leeyoon and pit Sohone against Mune. Meanwhile, Mune struggles to maneuver the Temple of the Moon, and Necross sends Mox and his partner Spleen to steal the Sun. As a result, night falls across the land and Mune is banished from his people. Mune and Sohone set out to find the vanished Sun, with the wax girl Glim accompanying them. While in the Great Blue Hole, a lake containing an entrance to the depths of the world, the group meets Phospho, a former Guardian of the Moon from the same generation as Necross who gave up his position after failing to stop him. He leads them to the entrance of the Underworld before leaving. Meanwhile, Leeyoon takes Mune's place in the Temple of the Moon, but is unable to control it. The Moon wanes and crumbles, causing the Temple to go out of control and fall into the Underworld, where Mune, Sohone and Glim are. Mune and Glim take care of the Moon while Sohone dives into the Underworld to recover the Sun. Mune figures out that he can calm the Temple of the Moon by using his powers, inspiring Phospho, who had watched from afar. Leeyoon admits to him that the Moon is lost, but Mune and Glim go into the Moon Quarry, which Yule had informed Mune of before dying, to create a new moon. Mune and Glim develop feelings for each other as Leeyoon apologizes to Mune, recognizing him as the true Guardian of the Moon. With the task done, Mune and Glim rejoin Sohone in the World of Darkness and find him surrounded by Pale Snakes attempting to corrupt him. However, Phospho intervenes and sacrifices himself to rescue Sohone and destroy the Snakes. Sohone, Mune and Glim confront Necross and his Imps while Glim finds and revives the Sun, melting in the process. As Necross is about to crush Mune and Sohone, the Sun and the Moon unite and empower them. After Mune uses his Dream powers to defeat Necross by putting him to sleep, Mune realizes that a Pale Snake was influencing Necross, Pulls it out of his body and destroys it, Freeing Necross from his control. This restores him to his original appearance and transforms him into a statue as the Underworld becomes a paradise. Afterwards, the two Guardians restore the normal trajectories of the Sun, the Moon, and their Temples. With help from the Sun and Moon's power, Mune revives Glim and gives her the ability to maintain her body regardless of temperature. Mune and Glim meet up and kiss before going around the world on the Temple of the Moon. ==Voice cast==