Although it's a very lazy practice, this is exactly how many Japanese sites (and internet services) fight against bad actors. In short, they block non-Japanese

Although it's a very lazy practice, this is exactly how many Japanese sites (and internet services) fight against bad actors. In short, they block non-Japanese traffic and data center IPs. I expect these measures to become insufficient as consumers adopt IoT devices and provide ample amounts of residential IPs for botnets. As for phone numbers, businesses and individuals employ a similar strategy. Most "legitimate" phone numbers begin with 060 or 070. Due to lack of supply, telcos are gradually rolling out 080 numbers. 080 numbers currently have a bad reputation because they look unfamiliar to the majority of Japanese. Similarly, VoIP numbers all begin with 050, and many services refuse such numbers. Most people instinctively refuse to answer any call that is not from a 060 or 070 number.