Osamu Oishi

Name: Osamu Oishi
Sex: Gender Neutral
Age: 36 (in AI and AINI Past) | 42 (in AINI Present)
Birthday: October 11
Profession: Tending bar, Selling information; Fortuneteller (AINI)
Likes: Loincloths; Switching, Making them touch (AI); Bali Riva, Sword Fighting
Dislikes: Hate crimes, Customers who throw up in the bar
Hobbies: Polishing bonito, Watching videos (AI); Shining Her Crystal Ball(s), Watching Hiraoka's Promotional Video
Skills: Has the uncanny ability to detect virginity (AI); Fortune-Telling, Guessing How "Big" a Guy Is

In AI: The Somnium Files:
Mama is the owner of the bar "Marble" in Golden Yokocho in Shinjuku. Date and Renju are regulars there and she knows them well. She is also an information broker in the criminal underworld.

In AI: The Somnium Files - nirvanA Initiative:
Past
The owner of the bar named Marble in Golden Yokocho. She knows a lot of information, even criminal or darker facts. Recently picked up fortunetelling and has received some praise for her accuracy.
Present
Over the past 6 years, her fortunetelling accuracy has increased. A few years ago, she had lines out the door, but it got to be too much for her and she banned everyone but repeat customers. Mama's amazing...

From the in-game character descriptions