For the purpose of deciding whether it is an openjaw or a stopover, the city matters. i.e. HND//NRT is regarded as stopover but not openjaw.

However, once ticket issued, you cannot change from one airport to another airport within the same city without triggering re-issue (if ticket is completely unused). In other words, you can't simply pay 1,000 asiamiles to change from one to the other.

The rule is a bit different for revenue ticket which the routing rule itself already allow NRT or HND as an alternate route.

The reason why airport is clearly distinguished for award ticket is because it may affect the calculation of miles needed. For example, CTS-KIX//HND-HKG falls under 1500-2500 band, whiles CTS-KIX//NRT-HKG falls to the higher 2500-5000 band. Asiamiles does not use TYO to calculate the distance.