MTL - Steel Shell System - v2 Chapter 315 Real artifact

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.

- Description from Novelupdates

The story is centred around a cute android who initially had a happy life with her master who dearly loved her. But she was then struck by a series of misfortunes and ended up in a robot-equivalent of concentration camp. Through experiencing and witnessing the sufferings towards herself as well as the people/robots around her, she eventually gained a better appreciation of life.

After being awakened from their slumber, billions of people found themselves dispersed in various sealed crypts. Surrounded by earth, they each had only a shovel.