15-year-old Saotome Sei has a tendency to fail at the worst moments, making her believe she was born with bad luck. After failing the entrance exam twice, somehow the only school that accepts her is one that has rigorous study and academics.
Her bad luck only continues when she fails tests in class, and she seeks solace on the school roof where she discovers an observatory occupied by the astronomy club. There, she meets student representative Udagawa Taiyou, who Sei keeping bumping heads with; and the kind, soft-spoken Ootaka Mizuki, who insists that Sei join the club because her name is the same as his favorite star. Is this the beginning of Sei’s luck finally turning around…?