NRT-CGK direct award flight is available in J for 23-30 Aug.
120,000 Avios + £60.10
From there you can get a very cheap flight on GA to DPS.

Personally I would rather pay 60k AA Miles +£60.10 though.
You can buy 72.5k AA miles during the current promo for $1327.50 FYI
(it doesn't make sense to buy less as you'll miss out on a huge number of bonus miles)

I did this exact trip myself and wrote a trip report here, if you're interested:

CGK-NRT on JL J
DPS-CGK on GA J