Born in 1432 as the son of Ota Sukekiyo, chief retainer of the Ogigayatsu Uesugi clan. He studied at the Ashikaga Academy and became accomplished in both martial and literary arts.
In 1457, at age 25, Dokan built Edo Castle on a strategic plateau overlooking Hibiya Inlet where the Arakawa and Tone river systems met Tokyo Bay. He simultaneously built Kawagoe Castle, establishing a military foundation for his lords.
During the Nagao Kageharu Rebellion of 1476, Dokan demonstrated extraordinary military genius, winning over thirty battles without a single defeat. His fame and power grew to surpass even his lord Uesugi Sadamasa.
Dokan was also renowned as a poet. In the famous "Yamabuki" anecdote, caught in rain during a hawking trip, he asked a farmhouse for a straw raincoat. A girl silently offered him a branch of yamabuki flowers — an elegant allusion to a classical poem suggesting she had no "mino" (raincoat/fruit). Moved by her literary sophistication, Dokan devoted himself to poetry.
On July 26, 1486, Dokan was assassinated at age 55 by his lord Sadamasa, who feared his retainer's growing power. Dokan reportedly cried "This side shall perish!" — a prophecy that came true as the Ogigayatsu Uesugi clan rapidly declined.
The castle Dokan built would become Tokugawa Ieyasu's seat of power 130 years later, growing into the greatest castle in Japan and the foundation of modern Tokyo.