MTL - Bancheng Fengyue - Chapter 141 city ​​of sand

A good-for-nothing man married a beautiful girl but was kicked off the bed on the wedding night. Furiously, he wrote a bill of divorce and ran away.
He was schemed a car accident in which he nearly lost his life. However, it turned out to be a blessing. He swallowed the soul that passed through the outer world, thus obtained superb medical skills and martial arts.
Later on, with the silver needles and invincible martial arts, he embarked on the road of counterattacks and was committed to his great dreams.

- Description from Novelupdates

However, he did not know that he was not raising just a harmless pet, but a biological weapon secretly made by the government… a real monster.

As a former librarian, Rand felt that he had been living an ordinary life, the one that he had reclaimed unconsciously every single day.

Recently, he has been a little upset because the pet fish he accidently brought home to raised seems to have undergo some strange changes

Well, it turned into a merman.

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You take up a student career.

Student career upgrade to lv.7

Acquired skills: primary school knowledge, junior high school knowledge, high school knowledge.

You take the college entrance examination,

You got a perfect score.

Your basic occupation has been upgraded to lv.9, and the job transfer system has been activated.

You change jobs to become a scientist, you gain R&D skills

You use research and development skills to get space fortress construction technology

You use R&D skills to gain starship technology.

You are invincible.

- Description from novelbuddy