Noboru Okamoto born February 15, 1932 in Tokyo, Japan), known by the pen name Sanpei Shirato (白土 三平 Shirato Sanpei), is a Japanese manga artist and essayist known for his social criticism as well as his realistic drawing style and the characters in his scenarios.

He is considered a pioneer of gekiga. The son of the Japanese proletarian painter Toki Okamoto, his dream to become an artist equal with his father started when he became a Kamishibai artist.

He is also known for his work published in the early issues of the manga anthology magazine Garo in 1964, which he began publishing so as to serialize his comic Kamui.