The battle against the Insectors to save the Inner World rages on, as Hunter Steele and the Spider Riders defend Arachna. With the help of his friends—Igneous, an intelligent young royal officer of Arachna's military; Magma, a foolhardy warrior; and Corona, a kind-hearted girl—crisis has been averted—but not for long.

News of the Kingdom of Nuuma being attacked by the Insectors is soon brought to the attention of the Spider Riders, who are reluctant to leave Arachna undefended. But past favors need to be repaid, so they decide to travel across the Inner Ocean to protect the Kingdom of Nuuma. Entrusted with finding four of the Oracle's keys locked away by the leader of the Insectors, Hunter and his friends strive to bring about peace once and for all.

Spider Riders: Yomigaeru Taiyou is the epic conclusion to the Spider Riders series. Will the four Oracle Keys find their way to Hunter and the Spider Riders, or will Mantid and the Insectors finally have their wish granted, conquering the Inner World for themselves?