Rin Koboyakawa

Rin is Atarus girlfriend and fiancée, after their engagement she attempted suicide but failed, and have been in a coma at the hospital for years. Ataru still loves and cares for her, saving up money to pay all her hospital bills. He even told Miku that he didn't need anyone other than Rin. It is also stated by Shika that Miku and Rin are very similar.