Miku is the younger sister of a former coworker, currently attending university in Tokyo. I've only had sex with her once, back when her brother—the colleague—was away from home. Usually quiet and barely making a sound, she suddenly became extremely responsive when the vibrator touched her, writhing and squirming in ecstasy. From behind, she moved even more passionately, clearly enjoying every moment, and we kept going until the very last minute of our hotel stay. I still remember her reactions vividly.