Rio and Mina are close friends. While taking a selfie together, just as the shutter clicks, Rio suddenly lifts Mina's skirt. To their surprise, Mina's panties clearly appear in the photo, causing her to instinctively crouch down and try to escape. Seizing the moment, Rio quickly pins her down. With Mina already crouched, she's easily flipped onto her back, her legs grabbed and spread into the forbidden electric massage position. As Rio begins applying the electric massager, she starts interrogating Mina with blunt questions. "Why are you even dating that creepy loner guy?" Mina snaps back, "So what? It's none of your business!" But Rio presses further, "Isn't he gross?" Mina then shocks her by confessing, "Actually, I recently used electric massage on that loner and made him climax over and over again, lol." Rio reacts with disbelief—"No way, you're lying!"—but Rio only smirks and taunts, "I'll show you how it's done later, just wait." This scene perfectly showcases Rio's mastery of the deadly electric massage technique. In 'DA189', popular girl Rio dominates shy, sensitive Mina with relentless seductive vibrations. Even after Mina climaxes once, mischievous Rio shows no sign of stopping. She combines electric stimulation with teasing tickles on Mina's inner thighs, mounts her to tickle her armpits when she writhes in ecstasy, and expertly halts stimulation just before climax—denying her release again and again. Helpless and hypersensitive, Mina is completely reduced to Rio's playful toy.