Please give me the name of a novel or manga!

The content of the novel was about a monster who came to the modern world to catch a girl for an exam. Who knew that the girl he caught would not pass? Later, in order to save the girl he caught, he exchanged bodies with that person. Then, he became a human living in the demon world. The monster originally planned to be punished for the human, but when he was punished, he opened the door of the modern world and went to the modern world. A manga was about a foreign student from the magic world who went to a human school. She was discovered by a female student using a magic tool that was similar to a computer. Later, they became friends. The magician often planned to use magic to help the female student, but he always screwed up. The magician also had an older brother. He remembered that once, they turned into cats.