MTL - Little Mermaid Dressed As a Scientist - Chapter 64

Previously one of the ten greatest Martial Emperor, Gu Feiyang somehow died near the mountains of Heaven Wave.

Fifteen years later, Gu Feiyang crossed through the cycle of rebirth. He was back! But this time, he was in the body of Li Yunxiao. Since then, Li Yunxiao started a treacherous journey. The world is in turmoil once more!

- Description from Novelupdates

Born with amazing talent and mastery of the sword, at age 13 he awakened his memory about the world thus setting out his own journey and create a world that is for himself and his crew onlyAt the age of seventeen, he went to sea, joined the Rocks Pirates, participated in the Battle of God Valley, plundered the treasures of the Celestial Dragons, formed his own pirate group, competed for the throne of the Four Emperors in the New World, and became the world's number one swordsman.The most powerful attack and the most powerful defense are gathered in one person, and finally became the strongest in the world.Before the war on the top, he helped Whitebeard restore his peak strength. When Whitebeard attracted the attention of the whole world, Li Yuan led his pirate group to attack the Celestial Dragon Holy Land Mary Geoise...

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.