"Then good," Dia says, swallows. The brush of thumb to nipple makes her stomach tighten, and she's quick to return it, focusing her own fingers' movements in turn. She pinches Mari's nipple, softly yet firmly, between the pad of her forefinger and thumb -- then she rubs it, kneads at it, hoping the elicit a similar reaction. She can already feel the flesh grow rough beneath her fingers. Ah...