I think you're seeing some yen defense at certain levels where Japanese "pension funds" (another word for the BoJ) are coming in both in yen crosses (primarily USD/JPY) and the Nikkei itself. It's pretty reliable lately, however. The Yen is moving lockstep with ES.
dude, no way... looks like 2 week chart of ES with after hours versus 2 week of usd/yen looks good for spotting divergences