Tsuiraku JK to Haijin Kyoushi summary:

Mikoto Ochiai is ready to jump off the rooftop of her high school's building after she got rejected by the boy she loves. However, her physics and home room teacher Jin Haiba suddenly appears on the rooftop for a smoke, talked to her and saved her from falling down. He even asked her to go out with him which made her confused. How will things go between the smart and calm Mikoto and her seemingly carefree teacher Jin?