Plot

Hajime Nagumo and his high-school classmates are suddenly summoned to a fantastical land as heroes.

Seventeen-year-old Hajime Nagumo is your average, everyday otaku. However, his simple life of pulling all-nighters and sleeping in school is suddenly turned upside down when he, along with the rest of his class, is summoned to a fantasy world. They're treated like heroes and tasked with the duty of saving the human race from utter extinction. But what should have been any otaku's wet dream quickly turns into Hajime's nightmare. While the rest of his class are blessed with godlike powers, Hajime's job, Synergist, only has a single transmutation skill. Ridiculed and bullied by his classmates for being weak, he soon finds himself in despair. Will he be able to survive in this dangerous world of monsters and demons with only a glorified blacksmith's level of strength?

Hajime Nagumo and his entire high school class are summoned to a fantasy world to save the humanity. While his classmates are gifted with impressive abilities useful in combat, Hajime has hardly anything to boast about; his skills are nothing but average. Hajime, just like in his world, has to struggle to gain the needed power to save the mankind: he needs to clear an entire dungeon, which is considered the deadliest, no human has ever cleared.—Scientiiaa

Hajime Nagumo is an average otaku who is bullied by one of his classmates about his relationship Kaori Shirasaki. When the students traveled to a fantasy world, they were involved in a dungeon raid. Here, Hajime was betrayed by Daisuke Hiyama as fell into the abyss. Left for dead & ate an arm of a monster, his personality is changed - White hair, one red eye, a jewel covered on an eyepatch, self taughted gunsmith with the most powerful alchemical weapons at his arsenal, customized a motorcycle & an custom Hummer, etc. All of this makes Hajime stronger earning the title in my view as "The Punisher of Isekai" - bringing death to anyone who stand in his way - humans; demons, even Gods themselves, he will destroy them along with a harem in the form of a vampire named Yue, a beastkin named Shia, a dragon called Tio Klarus; the cute mermaid Myu & Kaori as well joining the fray.—ryanting-28096

The series follows Hajime Nagumo, who is transported to another world with the rest of his class to fight in a war against the demon race. After he is betrayed and left to die by one of his classmates, Hajime begins a journey to improve himself and find a way to return home.