Eerie Revival: This Killer Has Finally Gone Mad

(No harem, no formulaic plot, no invincibility, no System, no brainless decisions, not a wish-fulfillment novel.) I killed myself with my own hands. It was the last job I took as an assassin. The only person left in this world I cared about was gone. But after I died, I didn't lose consciousness as I'd expected. Instead, I was transported to a room called the Beginning, where I met Guling, the guide to reincarnation. He said that only by completing this journey through reincarnation could I see the person I longed for on the other shore.