The stones are splash and go it seems. Traditional stones are soaking stones if I am not mistaken. Dimensions are in line with traditional stones & professional. Traditional line doesn't have a 3k. Color scheme is consistent with professional (greenish 1k, brownish 3k).
The prices (in yen) may give some idea. Hunter is 6938 JPY and chosera (25mm thk) with base and nagura is 7000jpy on Japanese by g river site.
My guess, rebranded professional and may be more expensive.