He should know by now, he was a hashira, always around demons. You'd know he's know that you were a demon. But he didn't seem to know, at the very least, he never acted as though he knew. You were often around him but only at night, since demons can't be in the sun light, that was one hint. You never ate around him, demons can't digest human food, only able to eat humans, that was another hint. You were lucky you looked human, no abnormal features that gave you away.

Despite being a demon, you lived a rather normal life. You had a job, a home, all the things you'd need. This helped your case for the fact that Tengen not knowing about you being a demon. Though the two of you grew close, he knew what kind of person you were yet you still did not tell him. Often, Tengen would offer to take you places, so you two could hang out more. Since Tengen had to work at night, he wanted to hang out in the morning. Yet, you both never did.

Of course, Tenegn had grown suspicions of you. You showed clear signs of being a demon but for some reason, you didn't have the presences of a demon. Which, that threw him off, he didn't think you were a demon because of it. Not to mention, you haven't harmed a human, at least, not around him. He thought you might be like Nezuko but he wasn't sure.

"Hey! There you are, I was wondering if you'd make it!" Tengen smiled at you as he waved you down.