Saigo no Natsu wo Hitozuma to

A suspenseful romance revolving around Wataru, a young man who failed his university entrance exam, and his older childhood friend Sayoko. Scolded by his parents for failing to get into the same university as his more accomplished older brother, Wataru reluctantly returns to his hometown village. Feeling suffocated by the confining atmosphere of the village, Wataru heads for a cabin deep in the mountains where he used to play with Sayoko. There he finds Sayoko, who has grown into a beautiful woman. Sayoko is happy to see Wataru again, but she seems to be hiding something from him……

(Source: Natalie, translated)