Toby and Rose are unexpectedly transported to Eternia, a realm of magic, where they face deadly creatures and discover they've been summoned as champions by deities. Toby, who was summoned by accident is left without powers and will not be sent back home by the deities. He joins the eleventh-grade group while Rose aligns with the twelfth. They learn they can sabotage each other but not "kill"  As Toby's group gains respect through quests, during a quest to investigate a cult disrupting a peaceful village, the group betray him to the cult, subjecting him to horrific rituals that transform him into Arachno, a monstrous goat headed spider demon. After his temporary transformation, Toby meets a mysterious old man, marking the beginning of his dark journey to exact revenge against his former group and the deities of Eternia for forcing him into this dark world as he finds a way home amidst Eternia's dangers.