01 / Octagonal hall
Hakkakudo stood in the grounds of Iwashimizu Hachimangu,then was moved onto a burial mound at the Shinto-Buddhist separation.

Built in the grounds of Iwashimizu Hachimangu in the Kenpo era (1213–1219), it was rebuilt by Toyotomi Hideyori in 1607 (Keicho 12). In 1870 (Meiji 3) it was moved onto the rear circular mound of Nishikurumazuka Kofun. The city describes its plan as a square with the four corners cut off, with few comparable examples.
- Founded in the Kenpo era (1213–1219)
- Rebuilt in 1607 (Keicho 12)
- Moved to its present site in 1870
- Nishikurumazuka Kofun: mound 120 m long

