Breakers - Chapter 217 - Chapter 45: Demon King #4

However, he did not know that he was not raising just a harmless pet, but a biological weapon secretly made by the government… a real monster.

As a former librarian, Rand felt that he had been living an ordinary life, the one that he had reclaimed unconsciously every single day.

Recently, he has been a little upset because the pet fish he accidently brought home to raised seems to have undergo some strange changes

Well, it turned into a merman.

- Description from Novelupdates

The person that Pei Zhen hates most in his life is the perfect Fu Sichen. Alas, life is full of surprises and unpredictability. One fine day, an accident turns Pei Zhen into Fu Sichen’s pet cat! As Fu Sichen’s pet cat, he makes a shocking discovery about his sworn enemy – a deep dark secret that the perfect Fu Sichen has kept hidden for years. Trapped in his cat body, Pei Zhen moves from one adventure into another while trying hard to find a way of turning back into his human self. When he finally does, the world as he once knew, has become a completely different place!

An alien race invaded the Earth on June 6, 2128. At the midst of this war, many nations allied with the alien threat and the war nearly wiped out the rebelling humans of the planet. At the edge of mankind's survival, the United Nations Army launched its forces to eliminate the immediate stellar threats that loomed over Earth.

General Seeker Carlean, commander and leader of the mission, risked and gave his life to destroy the immediate stellar threat. The battle was won though Earth lay in ruins. Perhaps mankind will live to see a few years of peace before the alien threat returns to wipe out their existence.

At the immediate aftermath of the stellar battle, the fallen Seeker Carlean awakens and finds himself at aged 17, living the peaceful life he lived 16 years before he died.

So begins a new game in the battle for humanity's survival.

The night is coming, and evil whispers in my ear:

“Give it up, history ends here, your efforts are meaningless… This is destiny.”

Hearing this, the young man drew his sword and stood up, shining brightly on Jiuyou.

“I am the destiny!”

- Description from novelbuddy