Hatsukoi Shinjuu

Fall from a building, fall in love. Shinji was a high school guy without a future. He went up to the roof of a building with plans to jump, only to run into his beautiful teacher, Shinanoya-sensei! Then she made a shocking proposal that would change Shinji's destiny... An exuberant tale of double suicide from the pen of a genius!!

(Source: Manga Box)