第 3 集: 愛子和理子在基太的房間發現一本挑逗雜誌後，與假人練習親密行為

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While searching through Keita's room, Ako and Riko find a dirty magazine featuring siblings in a threesome. Wondering if they may end up doing the same thing with Keita, they have a 'practice threesome' with each other while using a dummy to represent Keita. (Source: Wikipedia)