This keyword strongly suggests you're looking for content related to an adult audio work (doujin voice drama) from DLsite or a similar platform, featuring themes of sleeping twins with erotic elements.
The older twin is portrayed as lively, cheerful, and always eager to play games with the player. In contrast, the younger twin, Ren-chan, is described as cool, calm, and initially wary of the protagonist. futago suimin suyasuya ecchi rj01296782 upd