O (O) is located in Ginza's famous Porsche Building (Okumura Platz Building) and has a sister restaurant, SOL. The interior of the restaurant is inspired by the Bellaggi Hotel in Las Vegas and is very popular among hostesses. It is also the biggest box in Ginza, with a large counter, main hall, sub hall, and two VIP rooms, all equipped with LCD monitors. There is also a grand piano in the center of the main hall. The owner is a very talented woman, who is also the owner of its sister restaurant, SOL, and is reputed to have one of the best management skills among owner-mothers in Ginza. The owner-mama is a long-time Ginza hostess, but both establishments have a next-generation Ginza clientele, so they are recommended clubs for those who prefer a more casual atmosphere.