A woman in her forties boards the Shinkansen wearing a hoodie and jeans. Filming begins secretly as she quietly asks, "Can I change clothes?" She has traveled all the way from Shizuoka, seeking excitement due to an unusually routine sex life. She claims to be fully satisfied with sex once a month, lasting 30 to 40 minutes. This stems from her high school days in an all-girls school, where she never developed interest in sex despite having boyfriends. After retiring from club activities, she naturally lost her virginity at 17 with an 18-year-old boyfriend. Later, influenced by friends saying things like "A life without masturbation is incomplete" and "It feels good when you aim the shower at that spot," she experimented but quickly lost interest and rarely practiced it. This time, she won't masturbate—instead, she'll enjoy conventional intercourse. In her forties and with limited experience, she holds strong preconceptions about sex, believing 30 to 40 minutes is perfectly satisfying. She climaxes once from clitoral stimulation but then feels ticklish, unable to continue. Her previous boyfriend's sex sessions involved no foreplay and ended in about seven minutes total, which she felt was just right. She's rarely experienced prolonged stimulation, so today she hopes to try things she wouldn't normally do with her boyfriend. First, she's blindfolded and lies down, filled with mixed feelings of anxiety and anticipation. A smooth brush glides across her shoulder blades, making her gasp in surprise as she reacts to areas never touched before. Next, a damp hand strokes her, and she exclaims, "I've never been touched like this!" Her sphincter tightens repeatedly in response. As fingers stimulate her clit and reach deep inside simultaneously, she arches her back dramatically, and suppressed moans echo through the room. Overwhelming, prolonged pleasure floods her with unfamiliar sensations—before she realizes it, a large wet stain has spread across the sheets. "I didn't even feel myself gush. I was so overwhelmed I didn't know what was happening." Embarrassed by the large stain she's made, she's left in shock, questioning everything she thought she knew about sex: What had her previous experiences even been? Could she really transform like this? A raw, real portrait of a woman in her forties.