My slender, busty, sexually disturbed older sister gave me a vaginal massage voucher that allows me to have sex anywhere. (Fujimori Riho, DASS-425)

Riho Fujimori has a very high sex drive, which led to her being dumped by her boyfriend. Meanwhile, her younger brother, Takeru, quits his job and hides at home because he's being bullied. Ten years ago, Takeru gave Riho a handwritten "shoulder coupon," and while trying to motivate her brother, Riho also came up with a way to satisfy her own sexual desires. She showed Takeru the shoulder coupon, saying it was a reward for what she got back then—ten condoms. "My reward for giving you the shoulder coupon is a vagina coupon; use it to rejuvenate," Riho said, moving closer to Takeru.