The Terrible Couple (1980)

Aspiring to be admitted to a good university and to become a lawyer, Tasiro Yuusuke, a tenth-grader from Kyushu, enrols in a prestigious high school in Tokyo. Plans are made for him to live in his uncle's house, part of which is rented out while his uncle is abroad on business. A realtor's mistakes leaves Tasiro sharing the house with Kei Yamaba, the most beautiful girl in the school, who is also his classmate. There is the risk that their unexpected 'co-habitation' will be discovered by the school authorities. While he grows increasingly attracted to her, he is often irritated by her innocent and nonchalant attitude towards their predicament. They each develop other romantic attachments, but end up turning to each other...