During her school days, Kasumi was in love with a girl in her class. One night, during a school trip, she slipped into her futon and seduced her into a forbidden lesbian encounter. Years later, they meet again, and Hikaru —the girl from back then— has now embraced her lesbian identity. Disappointed to learn that Kasumi is married, Hikaru accepts an invitation to stay at her house. When night falls, she crawls into Kasumi's bed, just as Kasumi once did on that school trip, even though her husband is sleeping beside her…