Guang Yuxiao's sister Guang Yuhui passed away suddenly... A few years later in early summer. Himuro Kaoru returns to the town where she has been away for a long time, and reunites with her childhood sweethearts, Akatsuki and Kimuraya. But three years later, a huge and invisible gap has developed between them. One day, Xiao received an unsigned invitation letter, and she could also bring a partner. Is it Mi or Xin, should she live in silence, or should she seek the hidden truth?