Minamoto no Yoshitsune fled to the Oshu Fujiwara after being pursued by his brother Yoritomo, but on the 30th of the 4th intercalary month of 1189, Fujiwara no Yasuhira attacked his Koromogawa residence under Yoritomo's pressure, and Yoshitsune took his own life at age 31. Centuries later, Basho stood here and penned his haiku about summer grass and warriors' dreams.

Minamoto no Yoshitsune, hunted by his elder brother Yoritomo, took refuge with the Oshu Fujiwara. Worn down by Yoritomo's relentless pressure, the fourth lord Fujiwara no Yasuhira stormed Yoshitsune's residence on this hill on the 30th day of the intercalary fourth month of 1189 and drove him to take his own life. Yet Yoritomo would not pardon Yasuhira for having sheltered him: that seventh month he marched on Oshu himself, and Yasuhira, betrayed by his own retainer, was cut down. A century of Fujiwara rule was over. The obsession Yoritomo aimed at his younger brother closed Yoshitsune's life on this hill and brought down the Oshu Fujiwara with it.