Because Russell was originally in a rather urgent environment, after Deer Head had finished giving instructions, it let Bad Day take Russell away.
This time was Russell's first use of Babel's "door."
When he returned once more to "Between Thousands of Doors," Russell looked up at the dense multitude of doors.
He spoke softly to himself:
"...Deer Head, open the door that leads to the room I was in before."
In that instant,
Russell clearly saw a door, originally colorless, suddenly changing in shape and getting painted.
He walked slowly over and put his hand on the doorknob.
At this moment, Deer Head whispered gently in Russell's ear.
"[When you're free later, come find me again]"
"——Okay."
Russell paused slightly, replying earnestly.
Since he responded this way, he would undoubtedly go.
Creak.
With the barely audible sour sound, Russell carefully and slowly pushed the door open.
Before entering, he first opened a slight crack and carefully checked.