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This breeder has been trying to produce new type of Kawarimono. Although I know him personally, I have never asked how he crossed for it. Maybe,

Ochiba X Kigoi or Ki-Shiro( it has a yellow color hiban instead of Kohaku's red color)
It is very interesting the Igarashi Ochiba that you posted compared with these Ochiba pics.

(Left to Right) Female parent, Tosai and 2 years old