Canvas ~Sepia-iro no Motif~

Asou Daisuke is a high school student and a gifted artist - but he is currently suffering from a block, which keeps him from painting. His childhood friend, Tachibana Amane, who loves him deeply, persuades him to do a portrait of Kimikage Yurina, a girl with a heart condition, before Yurina undergoes surgery. In the process of rediscovering his art, Daisuke also realises the love that he and Amane feel for each other.

[From ANN]