Rätsel is the major antagonist of the 3rd season. She is acquainted to Jin Makata. She is cruel as a Giver, aiming to kill her opponents. This is due to her hate for puzzles, wishing to prove that they are not necessary. However, she had shown a much softer and childish side when being around Jin.
Her name, Rätsel, means riddle in German.
Jin and Rätsel had known each other for a long time. They traveled together after Jin had met Rook and Kaito. Not only does she remember everything Jin taught her, but she also knows many things about her mysterious teacher. Rätsel seems to have romantic feelings for Jin and is very determined to get his memories back. She is also very protective of him. In the past, Jin told her that she is missing something compared to Kaito and what she lacked was the ability to have fun with puzzles.