Demon Lord Attack Arc[]
Gale Gibson is a summoned otherwolder because he was still a child, he was deemed a failed summons. He was then sent to the Freedom Academy where he met with his now classmates and Shizu who became his teacher. After a year he then met with Rimuru who became Shizu's replacement as their teacher. Rimuru went to fulfill Shizu's dying wish to save the children so he, with the children, all went to the dwelling of spirits to summon higher spirits to possess the children and thus control the growing energy inside their bodies that might kill them. Rimuru ate the lesser spirits Gale summoned during the spirit summoning and transformed them into a higher spirit using Great Sage. The contents were mostly of Earth Attribute Abilities. Furthermore, after analyzing the flame spirit Ifrit, a pseudo-human personality had been created. Corrective ability from the unique skill Great Sage has been added. He places his hand on Gale's head and grants him the power. Through this, the contract with the spirit was completed within a single moment. After analyzing Gale's condition he confirmed that the rampaging magical energy was now at peace. Of course, his aggregate energy was still far higher than that of normal children. That is the result of spiritual energy and magical energy offsetting each other. Now, as he continues to grow he will be able to acquire many abilities.
OAD[]
When an outdoor training session occurs, Rimuru provides them with a Camping Car pulled by Beast Gnome that Gale had tamed. A teacher named Tiss is assigned to watch over Class S. During their session, thieves ambushed them, but the students managed to defeat them. They also confront a Spectre, but it is too powerful for them; however, the Primordial Noir saved them at the last second.
Human-Monster Interaction Arc[]
After learning that Rimuru is leaving, she and her classmates are saddened by the news, but they promise to visit ever now and then. From this point on, Tiss serves as their teacher in Rimuru's place.