This is the fortress of Momochi Tanbanomikami, who is said to be one of the three great ninja, and nearby is Seiunzenji, which is the place of his grave. Also, Shikibuzuka, which appears in the Momochi Legend, is here, and “enkiri kigan” (prayers for relationship ending) is still done today.

Momochi Legend
The legend says that once upon a time, in the time of the south (the southern capital was in Yoshino), Momochi Tambanomikami served the court in Yoshino as a northern warrior, and was in the protection of the imperial court. He fell in love with a female official, Shikibu, promising his future to her. With his service over, Tamba returned to Iga, and as her imperial service too ended, she was to go to him. When Tamba heard that she had departed, he counted the days and went to meet her in Shimagahara, but as she had taken a different path, they missed one another, and Shikibu arrived at Tamba’s fortress with her beloved pet dog, as Tamba was still away. Seeing the beautiful official, and knowing of Shikibu, Tamba’s wife was insane with jealousy. She spoke with the retainer and killed Shikibu, throwing her into an old well. When Tamba returned home, he recognized the white dog in his house as Shikibu’s and was suspicious, and the dog led him to the well Shikibu lay dead. Then Tamba’s wife cast herself into the same well and died. Tamba then had the well filled in, and had a mound built over the top, and then had a skimmia planted on that mound. Tamba then climbed into the Takano Mountain and became a monk, memorializing their grave. That is how the mound became known as both Shikibuzuka and Shikimizuka.