Imouto to Sono Yuujin ga Ero Sugite Ore no Kokan ga Yabai (translated as My Little Sister and Her Friend Are Too Erotic, My Dick Won't Go Down!) is an adult-oriented OVA series produced by Collaboration Works and based on a visual novel. Episode 2, titled "Brunette, Twin Tailed, and Huge Tits!? My Little Sister's Cute Friend, Riko Arc", is the final episode of the series and was released on December 29, 2016.
The episode focuses on Riko, the cute and flirtatious friend of Miu, the protagonist's younger sister. Riko, who has brown hair styled in twin tails and a well-developed figure, openly expresses her attraction to Kanata, Miu's older brother. During a study session at Kanata's house, Riko clings to him and flirts relentlessly, much to Miu's annoyance.
Kanata, while initially enjoying Riko's attention, begins to feel conflicted due to Miu's obvious jealousy. Riko, however, is determined to get closer to Kanata and even fakes a phone call to create an opportunity to stay alone with him. She hides in Kanata's bedroom, waiting for him to return, leading to a series of intimate and provocative encounters.
The episode explores the tension between the characters, with Kanata caught between his attraction to Riko and his responsibility as Miu's older brother. The story blends humor, romance, and eroticism, culminating in a playful yet dramatic conclusion.
