Cao Tzu is based on the Chinese philosopher Lao Tzu. Still, I say there are enough references to both cultures for MooShu to not be a single culture reference. The great turtle's name is Maruzame ( yes, sounds Japanese ) The Moodha ( Boodah , forgive spelling, please ) Philosophy came from India. ( Possibly by way of Tibet ). So there are other cultures besides Japan represented.
I still can’t pinpoint where Maruzame is from because while his name sounds Japanese, there aren’t any turtles in Japanese folklore like it. The two closest ones are from Hindu and Chinese mythology. I’m assuming it’s the Chinese one because of how Maruzame has several cherry blossom trees on their back. I never said it was a single reference to Japan, I said mainly.
Also while there are two versions of the Kirin, the one in p101 seems to be the Japanese kind. The Chinese depiction of Kirin shows them being partially covered in fire, while the Japanese one does not.