Sayuki lost her mother before she could even remember, and her father when she was a student... The family who ran the local dojo raised her with nowhere to go. Sayuki was brought up strictly by her stubborn stepfather, but as she got married and grew up... she gradually began to admire her obstinate and clumsy stepfather. One afternoon when her husband was not around... Sayuki accidentally injured her stepfather during practice, and as her anxiety and uneasiness grew, she forgot her guilt towards her husband and touched her stepfather's crotch...