My Entire Family's Gone Haywire! - Chapter 5

Going for a swim, she ends up in an ancient wild Beast World and ends up being brought home by a handsome wolf.

Lenny, an orphan from the Sector 41 slums, suddenly finds himself in possession of a rare and unknown affinity. It allows him to upgrade himself, using energy acquired from spirit beasts. But will he gain enough power to defend himself against those with every advantage he has never known?Explore the Western Alliance, where the Four Pillars rule supreme, and all vie for the title of the strongest faction. But when those sworn to protect the people fight amongst themselves, who will save them from the biggest threat they've ever known? And can one young boy, with no family and a handful of friends, survive all that chaos?

Entering Tokyo in the bubble era, in this strange era, the only familiar ones are Matsuda Seiko, Nakamori Akina, Kudo Shizuka…

- Description from novelbuddy

800 years ago, 3000 dimensional gates opened across the entire world. In that moment, it was as if 3000 different colored eyes opened across the world as hordes of monsters swarmed out of these gates like tears.

Some could destroy city walls with one strike; They had bodies the size of a giant and fed on humans

Some latched onto humans, absorbing their bodies’ nutrients and enslaving humans

Some infiltrated the humans’ cities, disguising themselves as normal human beings while feeding upon human blood to sustain themselves.

In a night, the Human race fell to the bottom of the food chain.

The world had turned into a paradise for monsters…

- Description from Novelupdates