Sano and Miyata, two childhood friends, are on a trip together in a resort hotel facing the Pacific Ocean. Miyata is devoted to conspiracy theories and he tries to get Sano to believe this idea. But Sano doesn't believe it, and they fight. As Miyata's phone keeps ringing all day, Sano loses patience and takes the call. It was a phone call from Miyata's father, who was saying unintelligible things, probably from dementia. Sano hangs up the phone in confusion and tries to go home with Miyata.

在好友宫田（Miyata）的陪同下，佐野（Sano）回到了日本的海滨度假胜地伊豆，五年前他在这里爱上了如今已故的妻子的凪（Nagi）。佐野初次邂逅亡妻的海边旅馆如今濒临倒闭，他重返故地，试图找回一顶五年前丢失的红色帽子，那是彼时爱的信物，也是此时失落的证明。