King of Gods - Chapter 1489: Paramount Scripture

Freshly turned eighteen, John Newman, a helpless nerd, suddenly gets video game abilities granted to him. A mysterious higher power, a secret Abyss of magic beneath the surface of the normal world, mages, martial artists, eroticism, tragedy and a harem of hot girls awaits.

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!

Yu Shanshan, who has been tyrannical and lawless for 20 years, suffered retribution at the age of 21. She changed from a little ballet princess of 45 kg to a poor and fat one of 90 kg.. Apparently, eating was the most important thing in her life. Her success in losing weight was far away.

However, one day, the father of her child who had disappeared for four years came back. From then on, Yu Shanshan was forced to embark on a diet that was worse than death.

- Description from Novelupdates

Our protagonist Caam is a man from Earth that was reincarnated into this world as a demon. In order to survive, he spared no effort in avoiding the sparks of battle and without noticing it, he became strong himself.