Nagami Gakuen is a former girls-only boarding school in the outskirts of Nagasaki. Hart is the only boy in the gardening club, joining the flower-loving Kureha, reliable leader Rie and tomboyish Christina. They water the flowers, take care of the greenhouse, transplant the flowers every now and then, and bring flowers and fruits as presents to the adjacent hospital. The chapel that they call the club room, the gardens and greenhouse, and pretty uniforms were not all that they had inherited from the horticultural classes which were abolished with the introduction of co-education. They also carried on their volunteer activities at the school. Recently, there are rumours of a suspicious person in the school grounds, so they have been tasked with finding and expelling them. However, Kureha, who had known Hart since she was a small child, asked him if that suspicious person is actually him. That’s because he is secretly a ‘vampire’.
