She just wants to start fresh so she can graduate in peace. She just wants to leave behind all the bad memories—her sleepwalking, the trauma from being bullied at school—all of it. She did everything she could to keep to herself, but the class president, Hae-on, just won't leave her alone. One day, when Seulbi visits the local lake Hae-on recommended, she comes across something she never imagined seeing in her wildest dreams: a wild, dark mermaid.

(Source: Webtoon Entertainment)