Haru no Uta

Originally published in February of 2016 to 2017 by 月刊flowers (monthly flowers), only available in print. Re-released by the author on their twitter.

Midori Okamoto is assigned the task of observing fellow student Haruo Shimura, who rarely ever comes to school. Intertwining herself with him and his younger brother, she soon finds out they can hear the voice of plants.