Lunatan: 10,000-nen no Himitsu

Mokugyo, a fish with plant life growing from his back, and Toriiruka, a talkative creature, live in an underground world. They are joined by Harry, a lonely needle-covered animal, and Yona, a descendant of the ancients entrusted with the rebirth of civilization.

Ten thousand years ago, a giant tsunami destroyed a prosperous civilization that thrived thanks to giants called Luna, who brought the energy known as Mana. Now, in the depths of the earth, Mokugyo and his companions seek to uncover the truth of what happened and find a way to safely return to the surface.