Born in 1160 as the fourth son of Sasaki Hideyoshi, a vassal from Omi Province (present-day Shiga). His father served Minamoto no Yoshitomo, fled after the Heiji Rebellion (1159), and settled near Yoritomo's place of exile in Izu. When Yoritomo raised an army in 1180, Takatsuna joined with his father and brothers, serving in the campaigns to pacify Kanto and destroy the Taira. His immortal fame came at the Uji River crossing in January 1184, when Yoritomo's forces set out to destroy Kiso Yoshinaka. Riding "Ikezuki," the prized horse gifted by Yoritomo, Takatsuna raced against Kajiwara Kagesue's "Surusumi" to be first across. Takatsuna tricked Kagesue by warning him that his horse's crupper was loose; while Kagesue checked, Takatsuna plunged into the river and won the race. Warriors on both banks reportedly cheered. This episode, vividly told in the Tale of the Heike, became an enduring symbol of warrior honor. After the Taira's fall he became guardian of Omi. He reportedly took Buddhist vows in his later years and died around 1214.

Brave and honor-driven. In the Uji River race, he outsmarted Kagesue with clever tactics, showing both valor and wit.

The Uji River crossing race is immortalized in "The Tale of the Heike." Together with the famous horse Ikezuki, it remains an iconic tale of warrior valor.