I am thinking about changing my NH C flight from NRT to SGN because of the limited menu/seats to HND to a redeye flight via BKK or SIN. What would you change it to if at all? I arrive NRT at 3 PM and those flights leave late at night. Are there full services on those intra Asia redyes? Worth the trouble of getting from NRT to HND>

HND-BKK in F on TG (Get FCL access)
BKK-SGN in Y on TG

HND-SIN in C on SQ
SIN-SGN in C on SQ