Based on the blockbuster doujin series Until Summer Ends by mon-petit (art: もんぷち), this adult animation brings the "End of Summer" arc to life. High school girl Yui makes a painful sacrifice to protect her boyfriend Kou's athletic dreams—agreeing to submit to a perverted teacher's twisted demands. What begins as reluctant submission spirals into overwhelming shame, conflict, and forbidden ecstasy, gradually transforming her into a willing vessel of depravity.