I felt like the reason the other demons were confused by Leo's Missing Person Poster in one of the previous chapters was because the current him was too different from the past him. If there were any demons around Leo's age in that place, they would probably be more used to the old Leo rather than the current one. Not to mention he changed his clothes and magically grew out his hair. Most of the demons in Leo's home town also happens to act a lot like past Leo, now that I think about it. I don't think Leo really went home for visits in the past either since he did mention that he didn't like his hometown, while he was on the train. I think there was also one chapter that mentions that he rarely leaves the castle. I believe it was the one where the Princess was running off to the human world to buy some pillow thing.