Hello, Green Days

Mikage, a graduate student in the Department of Botany, is shy and timid when it comes to love. One day, Mikage decides to become roommates with his financially challenged junior classmen, Nanahoshi. But, suddenly one spring day Mikage is confessed to by Nanahoshi – whose sweet personality differs from his scary appearance. For the first time in his life, Mikage is in a relationship, but he struggles to understand how to become a loving boyfriend.
(Source: Frontier Works, translated)