Koutetsu no Baby Leaf

Almost a year has passed since Tokio-sempai unexpectedly told Yousuke, a student and lover of plants, "I fell in love with you at first sight!" So every day, Yousuke is continually on the receiving end of Tokio’s relentless attacks. The handsome Tokio, who is also a good student and successful with girls, harasses Yousuke daily, pushing him farther and farther away ... or maybe...
(Source: Girls' Generation Scanlations)Included one-shot: Kamisama wo Yameru Toki