A bored Rimuru Tempest accompanies Diablo when he goes to meet with an old friend in the Netherworld. What will happen when he meets an out-of-place human boy who piques his interest? (Tensei Shitara Slime Datta Ken and Mairimashita Iruma-kun crossover)

If you hear the word reincarnation nowadays, it is usually an untrue fairy tale of being transported into a new world and overcoming the greatest evil to bring about a glorious peace. Yet that unrealistic scenery gets pummeled by the extent of reality. A world too cruel where strength was all that mattered and moral principles were unimportant. The life of the weak is as cheap as dirt. Everyone has died. The same goes for me. Yet again, the raging rides of fate shifted me into a new world once more. So... peculiar. Absurd. Cruel, even. The curse of immortality, stripped of the right to rest. Maybe I just have that lingering desire to live despite it all. Destruction shall befall those who gets in my way. Permissiveness I shall embrace. Nonintervention to those who knows their place. A new reality's beginning... heralded by life and death.