Mawari accidentally learns Sun lives with Nagasumi and that Sun's parents are also their new teachers. After the Class Rep accidentally spills water on Sun, Mawari briefly notices Sun's tail, coming to the conclusion that Sun is a fish. She continues trying to splash Sun with water in order to verify her theory, but Nagasumi constantly protects Sun, while at the same time trying to stop Mawari from learning the truth so she won't be executed under the mermaid code of law. Mawari next uses cats to try and expose Sun for what she is but when Nagasumi points out how much her actions are upsetting Sun Mawari relents. At that moment Mawari is almost hit by a car and both Nagasumi and Sun save her together. In the hospital Sun ends up getting wet but this time Mawari steps in to prevent Sun's mermaid form being revealed and apologises for causing Sun so much trouble.