Death March kara Hajimaru Isekai Kyusoukyoku (WN) - Book 3 - 3-5. The Japanese in Different World

Having being plagued by same dream for the past six years, Chu Yanshen discovered a little boy who looked just like him out of the blue. It was only then did he, Chu Yanshen, learn that he had been deceived by the little lass six years ago…

- Description from Novelupdates

You had taken up the Student profession

You had now reached level 7.

Acquired skills: elementary school knowledge, junior school knowledge, and senior high school knowledge.

You took the university entrance exam and scored full marks.

Your have been upgraded to level 9, and you have activated the profession-change interface.

You became a scientist and gained R&D skills.

You used R&D skills and gained space fortress-building technology.

You used R&D skills and gained starship technology.

You are now invincible.

After 2000 years has passed, the ruthless demon lord has just been reincarnated! But his aptitude at an academy for nurturing candidates for demon lords is, “Inept”!?

At home, she was invisible; after marriage, she was a decorative vase; in the end, a sea of flames buried her, and not even her corpse remained. This is the portrait of Han Yuxi’s previous lifetime. Given a chance at rebirth, she strives to improve herself, wishing only to no longer serve as a foil or a pretty face. Then, she will seek out an exemplary husband and live a life of peace and prosperity. Alas, things turn out contrary to her wishes—she marries a man who bears a blood feud and hatred as deep as the sea. She turns the world upside-down, but her road to happiness is strewn with setbacks and the sweetness that comes after bitterness.