Animated graduation work by Touko Yatabe from Musashino Art University.

One day, Rintarou breaks the konoha fossil that his father cherished. Without being able to tell the truth, a feeling of guilt lingers. In the usual riverbank, where I was digging fossils, I met a strange boy, Toshi... A small fantasy of a summer woven by two boys and a stratum accumulates memories.

(Source: Video description, translated)