144 hour visa route question

Would I be ok with the following plan for the 144 hour visa?
US citizen on the following route...

Honolulu -> Tokyo - Visiting a few days (direct flight)
Tokyo -> Shanghai - Visiting a couple days (direct flight)
Shanghai -> Honolulu but with a short layover in Seoul

Does this layover in Seoul cause any issues? I also see available flight bookings with a layover in Seoul from Tokyo and to Honolulu, but that seems like it would be a problem?

Like this:
Honolulu -> Tokyo - Visiting Tokyo a few days (direct flight)
Tokyo -> Shanghai but with a short layover in Seoul - Visiting Shanghai a couple days
Shanghai -> Honolulu but with a short layover in Seoul

Thanks in advance