Falling High School Girl and Irresponsible Teacher

After a heart-wrenching attempt to confess her feelings to her first crush, high school student Mikoto Ochiai stands on the edge of her school's rooftop, contemplating a leap. Just then, Jin Haiba, the laid-back physics teacher often the target of student jokes, appears. Instead of trying to talk her down, he casually lights a cigarette and asks her to share what drove her to this moment. To Mikoto's surprise, he proposes that she embark on a fleeting romance with him before making any drastic decisions. As they navigate their unexpected connection, they start to explore the reasons for living and the complications of love.