Shiou no Kikan: Moto Yuusha no Ore, Jibun ga Soshiki Shita Chuuni Himitsu Kessha wo Tomeru Tame ni Futatabi Isekai ni Shoukan Sarete Shimau
Return of the Corpse King: Reining in My Cringe Secret Society·屍王の帰還 ～元勇者の俺、自分が組織した厨二秘密結社を止めるために再び異世界に召喚されてしまう～
Hizaki Shio was once summoned to a fantasy world where he defeated the Demon King and returned to modern-day Japan. Now a high school student, he's been pulled back into that world after three years. This time, he must stop a secret society called Helheim. The problem is that Shio created Helheim during a cringeworthy period when he called himself the Corpse King. He's horrified to see his old group being used by someone else and growing in power. He must face the consequences of his past actions. His first mission takes him to the Steel City of Gaghiel to rescue a noble heiress.