This Japanese Monogatari Isn't Lame - Chapter 6 - . I’ll Help You

Rainer, an amateur arcanist and college student, sought to create a new spell far surpassing the magic of the few he inherited from his grandfather. Yet the interference of an unknown event during the casting of his spell led him to be thrown through space and time.

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.

Yin Shen’s name is God.

He never thought that one day he would really become a god.

- Description from novelbuddy

Ding Ning was just an ordinary youngster from a small border town in southwest China, but he had learned tremendous medical skills from his masters since his childhood. After graduating from college, he stayed in Ninghai City and tried to seek a job in a hospital there, but things did not go well at first. However, he accidentally saved Shen Muqing who was from a rich and powerful family, and then got involved in the confrontation between Ninghai special police team and a mysterious organization called Vampire Mercenary Group in order to protect Ling Yun who was his landlord’s daughter. It became the turning point of his life. After that, he started an incredible adventure during which he would find out the real identities of his father and masters and discover the secrets behind the mysterious organization Vampire Mercenary Group and the special weapons and tactics team Dragon Soul…The story tells about how he opened nine apertures, fought with rogues, chased after various pretty girls and established a rich and powerful family by himself. He climbed up to the peak of his life step by step, and finally became medical sovereign.