From MangaHelpers:
Souichi is an art student, and one day he saw an amazing painting at his university that made him want to study under the artist. When he went to learn from the master, though, the man did not accept him. Shortly afterward, he met the man's granddaughter, a blonde-haired, blue-eyed child called Rune. She was a very energetic kid who drew Souichi into playing with her in the surrounding countryside. Soon, Souichi learned the truth--the painting he had been so impressed with at his university was not the grandfather's work, but Rune's. She is the artist from whom he needs to learn.