Yōichi, Yoichi or Youichi (written: 陽一, 洋一, 羊一, 與一, 曜一 or 要一) is a masculine Japanese given name. Notable people with the name include:
Yoichi Akiba (秋葉 陽一) (born 1983), Japanese footballer
Yōichi Amano (天野 洋一) (born 1981), Japanese manga artist
Yōichi Aoyama (青山 陽一), Japanese singer
Yōichi Asano (浅野 洋一), Japanese photographer
Yoichi Doi (土肥 洋一) (born 1973), Japanese footballer
Yōichi Erikawa (襟川 陽一), Japanese video game producer
Yoichi Futori (太 洋一) (born 1982), Japanese footballer
Yoichi Hatta (八田 與一) (1886–1942), Japanese engineer
Yōichi Higashi (東 陽一) (born 1934), Japanese film director
Youichi Imamura (今村 陽一) (born 1976), Japanese drifting driver
Yoichi Kajiyama (born 1971), Japanese footballer
Yoichi Kamimaru (神丸 洋一) (born 1984), Japanese footballer
Yoichi Kato (加藤 陽一) (born 1976), Japanese volleyball player
Yōichi Kobiyama (コビヤマ 洋一) (born 1959), Japanese voice actor
Yōichi Kotabe (小田部 羊一) (born 1936), Japanese manga artist and animator
Komori Yoichi (小森 陽一) (born 1953), Japanese academic
Yoichi Kuroda (黒田 洋一), Japanese environmentalist
Yōichi Masukawa (増川 洋一) (born 1978), Japanese voice actor
Yōichi Masuzoe (舛添 要一) (born 1948), Japanese politician
Yōichi Midorikawa (緑川 洋一) (1915–2001), Japanese photographer
Yoichi Miyaoka (宮岡 洋一), Japanese mathematician
Yoichi Miyazawa (宮沢 洋一) (born 1950), Japanese politician
Yoichi Mori (森 陽一) (born 1980), Japanese footballer
Nasu no Yoichi (那須 与一) (c. 1169 – c. 1232), famous Japanese samurai archer
Yōichi Numata (沼田 曜一) (1924–2006), Japanese actor
Yoichi Okamoto (1915–1985), American photographer
Yōichi Sai (崔 洋一) (born 1949), Japanese film director
Yoichi Takabayashi (高林 陽一) (1931–2012), Japanese film director
Yōichi Takahashi (高橋 陽一) (born 1960), Japanese manga artist
Yoichi Ueno (上野 陽一) (1883–1957), Japanese business theorist
Youichi Ui (宇井 陽一) (born 1972), Japanese motorcycle racer
Yoichi Wada (和田 洋一) (born 1959), Japanese chief executive
