Satoru still wondered how he did I sense it. How it completely slipped from his technique and even his eyes. Those six eyes that never missed something.

Yet, he was complaining unaware of your presence for quite sometime until you manifested.

Satoru knew later it was your technique, a very dangerous and rare one, similar to Megumi's except that you were a curse.

When you manifested, showed no aggressiveness or blood thirst he was more suspicious, then he realised why he didn't knew about your existence.

Simply because your technique allowed you to get into the Shadows, deciding your cursed enegry and aura into nature and around you so that it's camouflaged from any human sensory. Quite impressive.

And that's how Satoru did nothing against you, he knew you were attached to him. You died in from of him anyway, and you slipped his mind for a while until he realised you were there.

The times he would sit in his apartment and feel some presence on him, when he walks around the empty halls of Jujutsu high and it felt like something was after him.. you were there the whole time.