What does an IP country of Japan mean?
A database assigned the address to Japan. NTT, KDDI, and SoftBank account for most retail lines. A Tokyo pin on a national network is often the hub, not the town.
JP
IP addresses in Japan
What a geolocation country of Japan tends to mean, and which networks sit behind it.
Japan’s numbers come from APNIC. The retail networks are NTT (OCN and related services under AS4713), KDDI AS2516, SoftBank AS17676, IIJ AS2497, and NTT Docomo AS9605 on mobile. A Japanese country code plus one of those ASNs is the usual home or mobile case. A Japanese country code on a cloud ASN is a Tokyo region server, which is a different fact.
Japan deployed IPv6 early, and a lot of NTT fiber reaches the home with MAP-E or DS-Lite rather than a dedicated public IPv4. The symptom is the same one CGNAT produces elsewhere: the router’s IPv4 is not the address this site shows, and inbound IPv4 does not work. The IPv6 prefix is the one to use for reaching the premises. City databases over-predict Tokyo. That is a hub pin, not evidence the line was installed in Tokyo.
The regional registry is APNIC. What is my IP address · IP location wrong?
Further reading: Cloudflare Radar.
Questions
Why is IPv4 shared on some Japanese lines?
NTT and others have used MAP-E or DS-Lite: IPv6 to the premises, and a shared IPv4 for older services. The public IPv4 is then not unique to the household.