Konoha's Tag-System Ninja - Chapter 2 - : Scholar!

Mo Tianliao was a master weaponsmith and a demonic cultivator. When news spread that he was about to complete a divine weapon, cultivators from both the demonic and orthodox sides chased him down and killed him. In a stroke of luck, he managed to possess a new body and was reborn.

So what was the first thing on his mind after his rebirth? Avenging his death? Taking over the world?

Mo Tianliao: I have to find my cat!

—
Mo Tianliao: Why won’t you let me hug you? You used to be my cat!

Master: (unsheathes claws)

Mo Tianliao: Ahaha, this disciple has too much respect for Master, this disciple can’t bear to let Master walk on the ground!

Master: (lifts paw, sends disciple flying)

- Description from Novelupdates

Yang Yang starved to death once, so after rebirth, he had only one wish: food and clothing.

However, in the blink of an eye, Yang Yang heard his uncle say that he had to cut open his stomach to take out the eggs.

Yang Yang: … I advise you to be kind.

In order to protect himself, Yang Yang found out the identity of the father from the birth center, and he embarked on a road of no return.

Yang Yang: Duke, your family is in my hand.

A young unmarried duke: ? ? ?

- Description from Novelupdates

An ordinary (?) grandfather, Choi Chuntaek. In an effort to protect his granddaughter, he started the virtual reality game 'Arkstar.'

Then... he accidentally obtained a legendary class?

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.