Quickly travel back and forth and I’m living in all the worlds

Description

She was originally an ordinary person among all living beings, but one day the world was destroyed instantly. She became the only lucky one and came to a special world and became an eight-year-old child.
In just three days when she was at a loss, she experienced being found and sent to an orphanage, and then being adopted by an old lady, and then she was informed of the purpose of adopting her.
It turns out that there is such a strange rule in this world. Each family is only allowed to exist for two generations. Once there is a third generation, households will be divided. Each family is required to have a ten-year-old child to serve in the main temple for eight years, even if the child has Elderly families who served in the military and were forced to split their households now that their children have children also have to start having children in the military again.
After some questioning on her part, she got a general understanding of the world.
This world is managed by the main temple and assisted by the Quick Travel Bureau. The average lifespan is a thousand years.
After the old man had no problems with her, he made an agreement with her. She would raise her for two years, and after two years, she would serve for eight years.
Although she hesitated at a loss, she finally agreed. In her two years of life, she could only say that she had no worries about food and drink, and nothing else.
Two years later, she was sent to serve. The main temple was such a magical place. She actually worked sleeplessly for eight years. During this period, she could not rest even if she felt tired and sleepy.
The moment she walked out of the main temple, she almost cried with joy. She never wanted to go near this place again.
After being away, she still didn't know much about the world, but she had a basis for survival, an iron job that would last until she died as long as she didn't do anything illegal - an employee of the Quick Travel Bureau.