Keizo Oishi (Kanji: 大石敬三, Rōmaji: Ōishi Keizō) is the owner of Bunkado Antiques in Dobuita, Yokosuka. He is often absent from the shop, traveling around the country searching for antique art objects and old treasures. He is also the grandfather of Ryoko Nishizawa.
With over 40 years of experience, he has a sharp discerning eye for antique art and a extensive knowledge of Japanese antiques and artifacts. He also has a deep knowledge of Chinese antiques and carries a collection in his shop. He also is a collector of old books on history and unique martial arts move scrolls from various schools.
- Keizo's zodiac sign is Scorpio and he has a O blood type.