As an update, transfer passengers between terminals use the bus- there is no exiting immigration to get to your connection terminal. Process is easy & organized. Non-reving on 2 different airlines is an issue though. Most airlines will not board you unless you have a confirmed ticket outbound from Japan. If it’s the same airline both legs (e.g., UAL SFO-NRT-GUM) they may let you non-rev the whole way. But if it’s 2 different airlines, you have to purchase a departure from JP in advance.