Twelve-year-old Yuuta, still mourning his father's loss in a tragic accident a year prior, revisits a secluded dam in the mountains, a place filled with cherished memories of his dad. During a summer storm, he stumbles and blacks out, only to awaken in a mysterious village 30 years in the past, submerged beneath the dam waters. Yuuta's unexpected journey unveils a bittersweet 'alternate' summer break, blending nostalgia and discovery in a tale of time-travel.