Aroma is a Cool Type Idol whose brand is LOVE DEVI (previously Holic Trick Classic).
Aroma is a troubling girl who acts like a devil. She is also portrayed as an evil person who will do anything to achieve her goals, including petty tricks and sabotage if it suits the situation. She is portrayed as blunt and somewhat cruel, but she also cares for Mikan very much and values her friendship, even when she doesn't act like it. This stems from the fact that they have been together since they were really little and Mikan's presence is part of the reason why Aroma is the way she is today.
It was later revealed that Aroma acts this way to overcome her original personality - that of a shy and quiet young girl. By acting like a devil, she has been able to become more confident. However she is prone to breaking out of character, in which she abandons her archaic manner of speaking and speaks normally; only to get flustered after someone catches onto it.
(Source: PriPara Wikia)