If I run out of data what will happen?

5G Unlimited (KDDI): Stay connected under Fair Usage Policy — no daily 3GB cutoff.

4G Unlimited (NTT DOCOMO): After 3GB/day at high speed, speed reduces to 256 kbps until midnight JST reset.

Fixed Data plans: Once total data is used, high-speed access ends (5G fixed throttles; 4G fixed suspends connection).