This memorial marks the spot where the decisive clash between the Minamoto and Taira clans took place in 1185. Here, Taira no Tokiko plunged into the sea with the young emperor Antoku in her arms, rather than surrender to the enemy. The statues depict Yoshitsune (the victorious Minamoto general) and Taira no Tomomori, who tied an anchor to his feet and leapt into the sea at Dan-no-ura when it became clear that his side had lost.
It's across the road from the Mimosusōgawa bus stop.