Wish I'd seen this topic sooner, but better late than never. I've read all but six Claw appearances in Lev Gleason at this point. From what I've read and my notes on the stories, Claw was clearly allied with the Axis powers, but had a much closer working relationship with Germany than Japan. The two clearest examples of the Claw working with Japan I can remember are from Daredevil Battles Hitler (Daredevil Comics #1) and in Daredevil Comics #10. In Daredevil Comics #1, Hitler recruits Claw to the Axis cause and Claw ends up aiding the Japanese by destroying the Cha-See Dam in China and aiding the Japanese assault on Singapore. In Daredevil Comics #10 (which Roygbiv666 probably knows about by now since he's done a Ghost vs. Claw archive), Claw is called in by the German agent Kloglo to aid a Japanese fleet that has come under attack by American warships in the Pacific. In both cases, though, you'll note that Claw acted at the behest of Germany and you'll generally find Claw working with or through Hitler and Germany when he did aid or was aided by the Axis (and that was a rocky relationship, at best).
Just from a headcanon perspective, I always thought it made sense that Claw would be a little more distant from the Japanese Empire. The Claw's two known bases of operation were Ricca, an island in the mid Pacific, and Tibet. This means that The Claw and his forces operated out of regions where Japan focused their imperial ambitions. This would make Japan a more direct competitor for the Claw than Germany following a scenario where the Axis are victorious. Therefore, I would get why Claw wouldn't be too chummy with Japan even though this reason is never exactly stated. It's just my take based on their geographic proximity and the fact that Claw envisioned himself as being the sole world dictator following WWII.
Unrelated to Japan question, but just to touch on what Yoc mentioned about Claw being an alien invader, this happened in Boy Illustories #89-93 from May to Sept., 1953. This was Claw's big return to comics after his last Golden Age appearance in Daredevil Comics #31 (July, 1945) where Claw seemingly met his demise thanks, in part, to the efforts of his first nemesis Prof. Morris. In Boy Illustories #89, it's revealed that Claw originated from the planet Zylmarx. A gigantic chunk of that planet split off, it fell to Earth in Tibet, and Claw emerged from the crater it created. It then goes on to tell of how Claw helped the Germans build a rocket to defeat the allies in WWII, but, instead, Claw steals the rocket to return to Zylmarx. On his planet of origin, he spends years having the populace build his invasion fleet, and, when it's finished, he invades Earth to battle Rocky X and his Rocketeers for the fate of the planet. This story creates a lot of problems, though, as it retcons Claw's origin as told in Daredevil Comics #12 and his demise in Daredevil Comics #31.
