MTL - My Girlfriend is a Zombie - Chapter 1321 Side effects after using the sister

Xuanyuan was reborn into a strange new world where training to be a Xian was a cornerstone. There was however something ancient dwelling inside his body. He could now devour all of creation…

His name is Gao Yang (高阳), not a lamb (羔羊: gāo yáng), okay! If a gentle sheep gets upset, it will bite. Believe it or not!

Gao Yang a sheep in wolf’s clothes: Don’t come again! Otherwise, I will be rude!
Qin Shaoyan: Oh? Why not?
Gao Yang: I… I… won’t cook for you!
Qin Shaoyan: It doesn’t matter, just eat you.
Gao Xun: What if Dad dies after being eaten by Father? Waiting online, urgent!

- 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!

“I want to be a true demon.”

A boy not older than 20 years wished as he looked at the sky.

After suffering from the trauma for many years, he finally gave up on life.

People called him ugly, demon, and hideous.

He bared with it, but today he finally broke.

With a piercing pain in his chest, he died.

When opened his eyes, Logan found himself in another world and inside the body of a demon.

His wish was granted, but at what cost?

He had no power and was the lowest among the demons.

No one to help, no one to be with him.

But it did not affect Logan. Because he had something else with him.

‘Sin and Virtue System.’

Guiding him towards his goal to become a true Demon.

Logan’s conquest has begun, so be a part of it.

Otherwise, you will miss him.

The true Demon!

However, is the MC the 'only' one to have a system?

Hm?

Read the fucking novel and find out!