The Constellation Returned From Hell - Chapter 13

Every human on Earth was transformed into a summoned monster and was summoned to another world.

An extraterrestrial thing gives Chen Yizhe the ability to transform the microscopic world

Repair electronics?

To cure all diseases?

Modify DNA information?

Change the structure of water into gold?

Create new material?

- Description from novelbuddy

As a promise, he went out into the world as an assassin. 3 years later, after becoming the Supreme Assassin, he gave up on everything he had and returned to the ranks of ordinary people. But one day, Kismet, a mystical game created by the National Research and Development had appeared.

As a reward for preventing the assassination of the current king, Rou Coral is rewarded with becoming and escort of the Royal Princess Reaina who the boy adores so much. Thus begins his new life of servitude under his beloved high-headed Princess full of happenings and happy little accidents. Surrounded with Busty Head Maid, young Loli Princess and a Childhood Friend Maid, for the boy knight today is yet another day of struggle in this womanly paradise!!