Onshitsu

Jose is a student of a boarding school. His father gets remarried and Lange, a pretty blond boy, becomes his stepbrother. They stay in a second house in the countryside in summer while their parents are in their honeymoon trip. There’s a strange green house full of withered rose plants near the river… Jose falls in love with Lange, but there is a spirit in the greenhouse who wants Lange all for himself.

Was published in the 1976 anthology Alois.