I heard it is. But ususally, when in a drinking setting, everyone not underaged drinks the same, be it their 1st or 100th time, going from 0 to 10 as soon as they turn 21 (I think that's the drinking age).
My god, this woman barrels the camera and deadpan clarifies she's his soi-disant imouto in a way that doesn't diminish, but perhaps enhances the sincerity of the claim. I'm in love with her particular brand of crazy from the bottom of my heart.