As a Creature of the Abyss, I Can Travel Between Two Worlds!

Preface: Reverse-harem story

Synopsis: The apocalypse arrives, and a mysterious virus sweeps across the world. All of humanity is forced to evolve, but eighty percent fail and become zombies driven by instinct.

Among the twenty percent who survive, one in a hundred thousand awakens a superpower. Since most of them are women, they are called Valkyries.

When the mysterious virus descended, Eevee transmigrated to the Abyssal Blood Tide for unknown reasons. The moment he crawled out of his eggshell, he understood...

Only those who adapt to cruelty can survive.

P.S. As the title suggests, there are two storylines.