The basic storyline of Gravitation is as follows :

One night while taking a strole through the park, Shindou Shiuchi, a hopeful young musician, gets his lyrics insulted by writer Yuki Eiri.
      The story follows from that meeting. Shuichi forces his way into Yuki's life, and eventually, into his heart. Yuki is cold, as his name implies, and often tries to drive Shuichi away. But Shuichi's stubbornness gets them both through the beginning of their troubled relationship.
      AS this taks place, the two also have to deal with troubled pasts, music careers, way too protective brother-in-laws, and jealous competition.