Seiju no Kuni no Kinjutsukai

A man who failed job interviews and lived as a reclusive individual, Sagara Kurohiko, went to a mountain during a typhoon and was struck by lightning, dying as a result. He awakens in an unfamiliar land featuring a massive holy tree, and discovers his body has reverted to its teenage condition. Taken to an academy near the tree, he is accused of being a spy and brought before the headmaster. An incident occurs during transport, angering the headmaster, who prepares to attack Kurohiko with magic. Before the attack, Kurohiko notices and reads from an ancient scroll. As he does, four holes appear, and black chains emerge from each, restraining the headmaster. It is revealed that Kurohiko unknowingly recited a "Forbidden Art" incantation, a legendary and powerful technique no one has been able to interpret. Impressed, the headmaster offers Kurohiko a place at the academy.