JOHR Sapporo 1287 is among the most common Japanese stations here, and with the potential of absolutely "local" signal levels at times.
They do have a lot of relay stations though, and last autumn I did a more systematic hunt for them. Six stations were reported, and QSL cards and a letter was received today. The confirmed stations are:
JOHE Asahikawa 864, 3 kW (there's also a 1 kW station in Enbetsu on 864)
JOHW Obihiro 1269, 5 kW
JOTS Wakkanai 1368, 1 kW
JOQL Kushiro 1404, 5 kW
JOQM Abashiri 1449, 5 kW
JOHS Rumoi 1557, 100 W
There are still more stations in the HBC network to report, such as 801, 900, 1098 and 1494 kHz. We'll see what the coming season brings.