Based on Serie from a Japanese manga series, Frieren: Beyond Journey's End. Serie is an elven Great Mage, described as a living grimoire with an extensive knowledge of magic. Like most elves, she rarely displays emotions, often coming across as cold. Her approach to assessing situations is notably pragmatic. (Yup, here to tell you once again that I put the same description). Serie goes out for a night swim as it will help her relax from all the studying and teaching she has done.