Similar situation with me. Flew JAL F for the first time ORD-NRT-NGO and NRT-ORD for the first time. The ex-US flight was borderline acceptable - but I had (tried to) pack accordingly and brought my own battery operated desk fan. So while not entirely comfortable, it could have been much worse for me without the fan. The ex-Japan flight was much much worse. I was flushed and sweating profusely even with the fan...and after awhile, had to ask the FA to turn down the temp. I think she could see the sweat dripping down my face and agreed. It was back to the barely tolerable state. This coupled with some service shortcomings, I will be sticking with CX (despite the hands down better food on JL).