The name of the 'Oni-no-Iwaya Kofun' within the Saitobaru cluster …

A legend that it is the grave of a warrior who defeated an oni

A legend that an oni once lived there

A legend that an oni built it in one night

A legend that an oni is sealed inside it

The name of the 'Oni-no-Iwaya Kofun' within the Saitobaru cluster comes from what kind of legend?