Ji Su takes the first vacation in high school. In the summer class, she told Mi ji secrets that can't be shared with friends from her school. After a hot summer, there was a transfer student in Ji Su's class. It was Mi ji who knows her secrets. This brings big and small events to Jisu and her friends.

• Kim Nu-ri
• Kim Seo-yeon
• Lee Jin-sol
• Subin
• Kim Min-cheol
• Riho Minami