Mikoto and Shiki are making their way to Rotsgard Academy in hopes of opening a new store. Meanwhile, back in the demiplane, everyone is helping Mio practice her cooking skills by taste-testing her dishes.

We meet one of Misumi Makoto's classmates back on earth, who also has a curious encounter with a certain goddess who presides over a certain isekai. She and one other are sent there as heroes to help the hyumans defeat the demons.

Hibiki and Tomoki's parties prepare for the attack on Fort Stella (the one Makoto ended up being somewhat involved in against his will). The two human heroes couldn't be more different, posing challenges beyond the simple difficulty of facing the demons.

Makoto finally arrives in Rotsgard, but is shocked to find that he's somehow ended up registered to take a teacher's exam instead of one for students. On the way there, he crosses paths with some haughty students of the school...

Makoto starts planning his curriculum and class size now that he's employed at Rotsgard Academy. He wants to teach students to expand their use of elemental magic, but his first class seems to think that's simply impossible.

Makoto is finally able to open his new shop in Rotsgard, but convincing staff to work there rather than Tsige is a bit of a challenge. He later has a talk with Eva about this world's view of marriage, which doesn't sit well with him.

Makoto returns to the demiplane to check out his new house, which has finally completed construction. He arrives to find that the weather is unseasonably hot, and the source of the problem might be his fault.

Makoto had a busy but fun time in the demiplane. After finishing his business, he returns to Rotsgard with Shiki. Meanwhile, at Rotsgard Academy, Shifu and Yuno Rembrandt have returned to school and will attend a lecture with transfer student Karen Force.

Lime sets out to investigate hyuman experiments that are secretly being carried out in Rotsgard. He ends up being captured by an underground organization along with Eva. After that, the two manage to escape and meet up with Shin and the others.

Shin and company begin full-scale action to destroy the underground organization with demon general Rona's help. The group discovers that the mastermind is Bright, an instructor at Rotsgard Academy. Bright's willingness to make sacrifices angers Makoto.

It's summer vacation for Rotsgard Academy. Makoto spends his time doing miscellaneous work and learning magic. One day it's decided he will have a mock battle against the wingkin. Makoto braces himself against his powerful enemies who are undefeated.

One day near summer's end, the highland orcs are attacked by wolves and bears while exploring the forest. After hearing the news, Makoto goes to the forest in an attempt to make peace between them, but the bear he meets looks upon him with hostility.

The academy festival is fast approaching. Shinai, a temple priest, arranges a meeting with Makoto on short notice. Shinai informs Makoto about rumors concerning the medicine being sold at the shop and offers Makoto a proposal to help dispel them.

Makoto attends a luncheon on the second day of the festival and is approached by Sairitsu, an official with the Laurel Commonwealth. She suspects Makoto may be from another world because of the foreign characters on the Kuzunoha Trading Company's sign.

Students take on the individual competition in the school festival's highlight event, the combat tournament. Due to a nobleman plot, they are forced to face off against their peers. Jin advances to the finals and faces off against Ilumgand Hopleys.

Due to the incident with Zara, Makoto decides to join the demons, and after witnessing the fighting tournament, he decides to leave Rotsgard. The next day, Jin and his friends advance to the finals of the team competition and face a team led by Ilumgand.

Rotsgard's turmoil continues. Numerous mutants have appeared in the city and Jin and his friends attempt to subjugate them. Meanwhile, Mio, who has been ordered by Makoto to protect the shelter, detects a strange smell from Makoto during her mission.

The mutant turmoil shows no signs of ending. At the evacuation center, people who've transformed into new mutants have appeared, anxiety and fatigue have reached their peak. To change the situation, Misumi's group joins the mutant subjugation force.

Using the mutant disturbance as a decoy the demon army advances on the Kingdom of Limia and the Empire of Gritonia. The hyuman army tries to intercept them, but are quickly outnumbered and overpowered. The two great powers are on the verge of collapse.

Tomoe, Mio, and the residents of the demiplane are ordered by Makoto to take back Kaleneon, and enter enemy territory. Meanwhile, in the Gritonia Empire, Tomoki and his friends head to the battlefield, where they encounter Sofia standing in their way.

Makoto is shaken by the revelation that the hero he meets on the battlefield is his high school senior, Hibiki Otonashi. Unable to dwell on it, Makoto enters a battle with Io to whom he suggests the demons retreat, in order to avoid a pointless battle

Sofia suddenly barges into the battle between Makoto and Io. Having longed for a rematch with Makoto, Sofia launches a fierce attack on her nemesis as soon as she steps onto the battlefield. Despite being outnumbered, Makoto appears unfazed.

Outside Limia's royal castle, a fierce battle between Shiki and Mitsurugi unfolds. Meanwhile, inside the castle, the battle between Makoto and Sofia continues. Sofia, at a loss, unleashes her secret weapon.

After the battle in Limia, Makoto returns to the demiplane where he is welcomed by Tomoe, Mio and the residents of the demiplane. After a short celebration Makoto returns to Rotsgard to wipe out the remaining mutants, ending the days-long turmoil.