Chikan to nozoki: Hitozuma geshuku (1994)

Kosaku is staying with his older brother Koichi and his wife. This year is his third year of prep school entrance exams. In his sad youth, going back and forth between prep school and his study room every day, he had only one purpose in life. That was to peek into his older brother and his wife's bedroom... As he peeks from the storeroom next door, he begins to want to embrace his sister-in-law Misako, even though it's absolutely forbidden...