Someone bought a lot of US corporate debt in June

That at least is obvious from the TIC data. 

Moreover, the surge in buying did not come from Japan.  China’s purchases of corporate debt were up in June, but not by anywhere near enough.   Most of the surge in demand came from investors in Europe, and specifically from investors in the UK -- which doesn’t settle anything.   Since the UK runs a current account deficit, in aggregate, the “City” is not investing UK savings in the US corporate debt market. 

More later.