Starting with tracing Osaka's ancient history and it's origin;

The oldest historical heritage in Osaka's outskirts is " Chausu-yama Hill Ancient Tomb" with the shape square front and round rear, which was supposedly the tomb of ancient baronial family. It is estimated to have been built in the latter half of the 5th century, and is one of 3 existing large tombs with the square front and round rear.

The riverbed area on the south of "Chausu-yama Hill Ancient Tomb " is called "Chabu-ike Pond", and presumed a man-made channel constructed by Wake-no-Kiyomaro in 788 (7th of Eireki period ) to irrigate water from Kawachi ( Yamato ) River to Osaka bay after digging a moat in the south of Arahaka ( now Shitennoji or Chausu-yama Hill), however it ended in failure.

In ancient Osaka there was the inlet bay called Kawachi Lake between Uemachi-daichi ( plateau ) and the foot of Mt. Ikoma, and the bay gradually disappeared with built-up earth and sand as time goes by. Kawachi River is said to have winded its way from the east of Uemachi-Daichi to the north of Osaka Castle until the modern period.

Chausu-yama Tomb was built in the Tumulus period facing the sea with a superb view. Some archaeologists say " Naniwa Arahaka " described in " Nihon-shoki " should be " chausu-yama Tomb". In the latter half of 5th century " Chausu-yama Tomb " was constructed together with Tezukayama- and Okatsuyama-tomb at almost the same time.