Shinagawa was born in 1908 under the name of Takumi Sekino. He graduated from the Department of Metal Arts at Tokyo Metropolitan Kogei School. In 1935, while working at a printing company, Shinagawa started to study with the print artist Koshiro Onchi and learned woodblock printing along with more experimental techniques such as photogram. He joined the Japan Print Association in 1947 and the Kokugakai Association in 1949 and from 1952 onwards participated in various international print exhibitions. Apart of prints, he also created mobiles and three-dimensional works from everyday objects like spoons, aiming for a new experimental approach.