Pause System: Harem In The Apocalypse - Chapter 1

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 genius pharmacist transmigrated into a pitiful farm girl’s body. Ignored by her own father, abused by her stepmother, and bullied by her stepbrothers. Her “twin” brother was given to distant relative and she went as the “extra” to live under someone else’s roof.

Luckily she possessed mad apothecary skills. Collecting herbs, plowing herb fields, formulating medicines and treating the ills, she refused to live an ordinary life as she slowly uncovered the truth of her real identify.

Inadvertently, she saved a dashing man who was in reality a big, bad wolf hiding under the skin of an innocent little puppy. He pulled out all his tricks: I have no other means to return your favor of saving my life. What say I repay you by marrying you?

- Description from Novelupdates

There’s SIS in great Britain, CIA in the US. In Huaxia, there’s Dragon Division, known as the mysterious power of the East.

For unknown reasons, he finds himself transported to a parallel world's Japan, unexpectedly taking over the body of a soon-to-be high school student who had died accidentally. Surprisingly, he did not inherit any memories. However, the first challenge he faces upon arriving here is a language barrier...Just as he struggles to communicate with his new family, a heavenly voice arrives: the black technology system has been activated, and the initial item—translation konjac—has been distributed.This is the story of someone with above-average intelligence but almost no physical strength in the Classroom of the Supreme Power.