You've Got Mail: A Cautionary Tale - Chapter 103 - Visiting A Prisoner In Jail

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.

Let’s fight! Go! Who am I afraid of with a chip that turns into a brain cell? ! Get promoted and get rich! The nest treasures are all mine!

- Description from novelbuddy

Nyx, Earth's former number one mercenary found himself on the end of his life failing to escape from a powerful criminal mastermind. However, fate seems to have another plan for him when he woke up in a completely different place, a place that he will eventually call home in the new world where strength makes one the biggest boss.[Welcome to the Universal Shop System!][Detected that it is the first-time log-in. Reward: Random Gift Pack (5)][Detected the user entering the Body Tempering Realm. Reward: Infinite Qi System][Opened Random Gift Pack (5). Acquired True Transcendence Body Art (1). Acquired Primordial Nihility Transcendent Qi (1). Acquired Immortal Illusion Art (1). Acquired Grand Desolation Transcendent Body (1). Acquired Extreme Origin Transcendent Soul (1)]With an absurd system as his cheat, follow the young man's journey through the entirety as he gains his position as the one true peerless existence, the sole transcendent above all.

This is the story of a modern sailor who was accidentally reborn as a soldier of the Brazilian Expeditionary Force, and finally became the largest plutocratic family in Brazil by virtue of his foresight.

- Description from novelbuddy