Spider Riders: Oracle no Yuusha-tachi

A hidden underground realm known as the Inner World is home to warriors called Spider Riders, who battle using large spiders. A boy named Hunter Steel discovers this world after entering it through a pyramid, guided by information from his grandfather's diary. In the Inner World, a conflict rages between the insect squad seeking to conquer it and the Spider Riders. Oracle, a fairy of the Inner World, believes Hunter is destined to be a savior but is unable to act as her powers are sealed by Mantid, the leader of the insect forces. To restore Oracle's abilities and bring peace, Hunter must locate four sealed keys. With the help of Spider Shadow, a large spider selected by Oracle, Hunter joins the Spider Riders to fight against their enemies.