Hachidaiou, a Japanese name which translate to Chinese is the same a the Kanji 八大王 (pronounced Ba Da Wang, the Eight Kings/Lords). 大王八 can be literally translate into "Giant Tortoise". In the folktale "Hachidaiou/Badawang", there was once a scholar by the surname Feng from the Gansu province, who wasn't very rich but enjoyed helping people. He helps a former fisherman and receives a turtle from him, but he can't bear to kill it so he releases it into a river. A long time later, while visiting relatives, he gets into an argument with a drunken man. The man, Bādàwáng (Hachidaiou), realizes mid-argument that Feng was the one who saved him, and kneels at his feet. he gives him a treasure that grants the scholar super-human powers (the ability to see hidden treasure). Feng buys an old house some time later and sees all its hidden fortune and grows wealthy as a result.
"The 8th Great King, he is a turtle king that appears in Chinese folklore. He is said to have the power to bring wealth, and can transform into human form. He was saved by a fisherman named Ping Sheng, and in return, he gave the fisherman an orb that made him rich. Ba Da Wang is a heavy drinker, and the old tradition of Japanese fisherman feeding sea turtles sake before returning them to sea may be a remnant of that myth."