Since you already have 30K FOPs on JL metal, the best bang for your buck is probably cheap MH Z fares to Bangkok or SE Asia. NRT-KUL-DPS is available for 150,000 JPY and will yield ~13K FOPs. You could also do TYO-OSA-KUL-SIN and back for 150,000 JPY and ~12K FOPs.
If you can use a cheap award ticket to get there and back, there are even cheaper fares out of SEL to SE Asia and Europe -- ICN-KUL-SGN return for 105,000 JPY and ~11K FOPs; ICN-KUL-CDG for 155,000 JPY and ~25K FOPs. I believe you could also book an open jaw to return you to Tokyo for a nominally higher fare.