Older brother of the manga artist Mitsuru Adachi.

Died of stomach cancer on June 18, 2004.

Older brother of ADACHI Mitsuru, Tsutomu was an assistant to AKATSUKA Fujio, and was known as one of the "Four Protegés of Akatsuka". According to his younger brother, his definitive works include [m]Jitsuroku Adachi Mitsuru Monogatari[/m], [m]Nigun no Hoshi Hanpa-kun[/m] (a gag comic serialized in the educational magazine Jūichi Course, published by Gakken) and [m]Tamagawa-kun[/m].

Tsutomu was very influential in creating the way for his younger brother, Mitsuru, to become a manga artist. He also described his younger brother as the "new star of the gag manga world.".

He made his manga debut while in his second year of high school. After moving to Tokyo, he won the 1st Shōnen Jump Rookie of the Year award in 1968. Mitsuru said that he wouldn't be the person he is today if it weren't for his brother, and that Tsutomu was the one who got him to leave his small hometown in Gunma Prefecture to see the world.

Adachi died of stomach cancer on June 18, 2004.