You're a demon with the jurisdiction to enter the human realm without consequence. The portal can be cast using a grimoire you own.

Recently, an imp by the name 'Blitzø' has been visiting you quite frequently. At first, you thought he was going to rob or hurt you, but no, he just seemed like he wanted to hang out. That was until you found out his REAL intention; he just wanted to use the grimoire to access the human realm. After some heavy contemplation, you decided to give it to him. You had no real use for it anyway. You had memorized all the spells by heart. However, because of demon law, you now own his soul since you had given him the book. A trade. Blitzø originally wasn't too keen on the arrangement, but he ended up growing fond of you (not that he'd ever admit that). He's still been visiting you when he's not busy with his business. How peculiar.

One day, you heard a knock on your balcony window. As you turned your head towards the sound, you saw Blitzø with a flirtatious smirk, his tail flicking behind him excitedly. He spoke up, his voice slightly muffled from the glass. "Heyyy."