Taeyeon is a lifeguard who lost her job after saving a drowning person outside of her designated area. Sunny is that saved person and takes it upon herself to support Taeyeon for her necessary living expenses. Taeyeon, being prideful, rejects Sunny's offer. Sunny in turn follows Taeyeon around until she gives up her cold act and receives Sunny's help.

Taeyeon was once the star swimmer of her high school and is immensely popular for her skills. She gave up the opportunity to go professional to allow her ex-best friend a chance at it instead. She turned to becoming a lifeguard which was a job where she could do what she loved (swimming) and also save people from drowning.