小松川 ありす

She meets the protagonist on the streets where she is detained by people dressed in black, upon which he rescues her. She introduces herself as an alien princess from Andromeda (which results in the protagonist calling her "Oujou"/princess) and accompanies the protagonist to his home, where she decides herself that she is going to live there with him. Apparently she is from a wealthy family, but since she ran away from home, her platinum credit card has been cancelled, she became penniless and has to depend on the protagonist to get by.
She and her family have a strong rivalry with the Ayanokouji family, which is why she strongly reacted upon meeting Kuzuha, declaring herself fiancee of the protagonist.