My Beast Evolution System - Chapter 12 - . Into The Dark Forest.

“If I don’t die… I swear I will act on all my evil thoughts..”

Not exactly everyone’s typical thought when they’re about to die. What will a cowardly young man do when reincarnated with the evil powers to redefine his destiny? Can the natural kindness of human nature triumph over evil? Will he become the cold-blooded demon king of legend, or will he forge his own path and rain down another kind of terror?

- Description from novelupdates

Akira Kuromiya is just an average high schooler who gets killed by a robber. He wakes up and is now a chicken!? Even worse he becomes the familiar of a girl who's apparently the heiress of a powerful clan.

That was for a short while though, as he was abandoned and woke up to find out he, now she, is trapped in a deadly magical forest with all sorts creatures trying to kill her.

The world she finds herself is one of magic and monsters like the manga she's been reading. Akira, now Hinotori is trying to live her life as a chicken in another world!

The day of marriage. Lifting the sedan chair to the door, he lightly lifted the sedan curtain, but he saw no newcomer, only a piece of paper pressed under a stone.

Looking at her flamboyant font, his thousand-year-old pupils faintly spurted out a few flames. good very good. On his perfect and impeccable face, there was a faint smile, not angry but smiling.

However, no one saw the hidden chill in that smile. That woman dared to run away from marriage, he would let her know the consequences of doing so.

- Description from novelbuddy

Ruins stretched across the landscape in the apocalypse after the nuclear war.