Raita Mogu and his friend Miko Shironezu arrive on the remote island of Mongura to spend a week working at a resort. Mogu immediately feels uneasy, not just because of the arrogant attitudes of his new coworkers, but because of the mysterious holes that riddle the ground everywhere he looks. Suspicious emblems shaped like red spider lilies adorn the buildings, and the island’s inhabitants all wear deeply unsettling smiles.

The true threat lies just beneath the surface, hidden within the first meter of soil underfoot. Without warning, the danger erupts from below, violently attacking the resort workers. The source of the horror is soon revealed to be aggressive, killer moles. As the group falls into chaos, the idyllic work-study trip transforms into a desperate struggle for survival.

The main cast is led by Raita Mogu, a young man whose name shares the Japanese word for mole, and his capable friend Miko Shironezu. As the attacks intensify, the survivors, including coworkers like Mamizuka and Shimau, must contend with the subterranean killers and the growing suspicion that the islanders are hiding a dark secret linked to the moles and the eerie holes. When Mamizuka and Shimau vanish under mysterious circumstances, the group must question if a traitor is among them. Kirinji, refusing to believe her missing friend has turned on them, escapes from the group's refuge to search on her own. Mogu, determined to escape the island with every surviving member, is forced to venture into the dark forest after her, confronting the escalating horrors that await in the night.