Shizuka

Shizuka is a receptionist at a local spa. She suffers from stuttering.

Later, Shizuka is under threat from the less than savoury owner of the spa to be transferred to a brothel as he considers her useless as a receptionist. Allison happens to hear that and rescues Shizuka by paying her outstanding debt to the owner and takes her home. Shizuka insists on paying her back by being their maid.

Initially, Shizuka shows strong signs of the traumatic life at the spa, terrified by minor stuff and breaking down crying at the slightest misstake. As she learns to trust the family, and MC in particular, she grows into a more confident young woman. She also turns out to quite the little pervert once she gets sexually awakened.

As their relationship deepens, she start to call MC Onii-chan ("Big brother"), not that this precludes her from having sex with him.

Her mother is Asami. She has mentioned that she has two sisters (unknown who and where they are). Her father was killed by the Yakuza because of gambling debts. This was what prompted Asami to relocate to the states with Shizuka.

She and her mother have a hereditary "allergy" to bananas that causes their breasts to quickly swell up to gigantic proportions for a short time. They then somehow shrink back to their normal size without becoming saggy. (This is probably the only close-to-fantastical element of the story.)