Natural High's new work 'A Flat-Chested Younger Sister and a Busty Older Sister' breathes new life into the niche but fervently loved genre of nipple torture and nipple orgasms. The collaboration between Tsukino Kasumi and Minazuki Hikaru, continuing from their previous work 'School Trip Lesbian', showcases a chemistry that keeps viewers hooked. Particularly, the scene where Minazuki Hikaru transforms from a mischievous brat into a sensual woman is a masterpiece. The plot where the younger sister teases the older sister's ultra-sensitive nipples is a perfect blend of laughter and excitement. The quality of this work hints at the potential for a series, with the days of nipple development culminating in a surprising twist at the end. This is a must-watch!