The staff's staircase

A few minutes before "Onii-chan arrived."

Aito descended the stairs. The surroundings showed by the transparent walls progressively changed from the second floor to actual stone walls the deeper he went. Sometimes, he'd see the staircases used by challengers. 

Much like the ones accessible to challengers, the staff's staircase was light by small seafoam color light bulbs glued to the ceiling and the wall to his left. The wall on his right seemed to be solely kept for sighting the floors. 

Curious, he took a moment to touch the transparent wall while walking. Surprisingly, as if it were an illusion, the wall blurred as his fingertips entered it, creating ripples as it touched stone cold... stones on the other side.