These are from various unofficial sources. As always with utility radio, it's only as good as the people who've taken the time to research it.
JBx This block for common carriers other than NTT
JCx This block for NTT common carriers
JDx This block for NTT coastal stations
JFx This block for Fishery Radio Stations:
JFA Central Fisheries National Radio ("Chuo Gyogyo")
JFB Mugi Tokushima Prefecture Fisheries Cooperative Radio
JFC Fisheries Radio Association, Misaki, Kanagawa Prefecture
JFD Ishikawa Prefecture Fisheries Cooperative wireless [Ogi]
JFE Fisheries Radio Association, Okinawa
JFF Miyagi Prefecture Fisheries Wireless Corporation
JFG Yaizu, Shizuoka Prefecture Fisheries Cooperative Radio
JFH Tuna Fisheries Cooperative Associations in Mie Prefecture
JFI National Federation of Fisheries Cooperative, Hyogo Prefecture [Kasumi]
JFJ Unknown company
JFK Shimonoseki (Terrestrial radio facilities for fishing)
JFK2 Akkeshi Radio Association (Whaling)
JFL Fisheries Suzaki
JFM Kochi Prefecture Fisheries Cooperative wireless, Muroto
JFN Tobata (Terrestrial radio facilities for fishing)
JFO Fukuoka (Terrestrial radio facilities for fishing)
JFP Miyazaki Prefectural Federation of Fisheries Cooperative, Aburatsu
JFQ Makurazaki
JFR Radio Association of Fisheries, Nagasaki
JFS Aomori Prefectural Fisheries Cooperative
JFT Kamaishi Fisheries Cooperative Wireless
JFU Ishinomaki (Terrestrial radio facilities for fishing
JFV Kesennuma
JFW Fukushima Prefecture Fisheries Cooperative Radio, Iwaki
JFX Kagoshima Prefecture Fisheries Cooperative Radio
JFY Wakkanai ( Terrestrial radio facilities for fishing)
JFZ Kushiro Fisheries Cooperative (ship equipment)
