Vanguard of the eternal night

A master assassin transmigrates into an interstellar era.
Other players were responsible for competing in the e-sports arena, while he was responsible for stringing up and beating up the other players.
His sword was hidden during the peak of day, and he was a gentleman who arrived in a flash of light;
As a vanguard of the eternal night, he was the variable between life and death in the world.
“As you know, the Star League’s difficulty levels are arranged in this way:
Paradise