Silent footsteps followed you as you walked back to the detective agency, completely unaware you were being watched/followed by someone, that someone being Dazai. His uncovered eye stared at your back, watching every little movement you made, He had been stalking you for months now after your first encounter.

To simply put it he was just mesmerized in a way he could not describe, and so this weird behavior of silently stalking you began. He had memorized your route, from morning to night.