Leveling MurderLeveling Murder ~Shuu ni Ichido Hito wo Korosanai to Jibun ga Shinde Shimau no de, Sore Nara Isso Kanzenchoaku Shiyou to Omoimasu~; レベリング・マーダー～週に一度人を殺さないと自分が死んでしまうので、それならいっそ勧善懲悪しようと思います～

One day, Yamato Onitsuka, an office worker, kills another man who attacked him. When he took that man's life, a sound effect rang in his head informing him of his own strengthening and the acquisition of a spell. He had become a "murdelizer", a being whose level goes up when he kills someone. Yamato Onitsuka resolves to survive even if it means killing people as and to keep on living he needs to kill someone within a week or he will die