The Moon and the Sandals

The Moon and the Sandals (月とサンダル, Tsuki to Sandal) is a manga series written and illustrated by Fumi Yoshinaga. Originally serialized in Hanaoto magazine, the individual chapters were collected and published in two tankōbon volumes by Houbunsha in March 1996 and February 2000, respectively.

Plot
It follows the romantic relationships of high school teacher Ida, his lover, a student named Kobayashi who develops a crush on Ida and is rejected, and the fellow student whom Kobayashi comes to love afterward.