Mister Sun

The guards instinctively felt a numbness in their bodies and stood rigidly on the spot, unable to move a muscle.

It was then that a figure blurred into existence in front of the guards, shrouded in a faint black mist all over. With a swift motion, the figure snatched a crimson key from the waist of one of the guards.

Next, the figure dashed like the wind and threw open the iron door behind them, vanishing into it with a flicker.

Behind the iron door was a long, narrow stairway leading downwards, and the air was exceptionally murky, as though it hadn't been ventilated in a long time.

However, the figure ignored all of this, darted down the stairs, and after blurring around a corner below, disappeared from sight.

A moment later, from somewhere deeper down the stairway, several cries of alarm were heard, followed by silence.