Vespa mandarinia japonica
Shockingly large hornet (see fly at top of picture for scale) I passed this tree on two separate days and there was a hornet feeding from the oozing sap on both occasions. Would love to know what the superbly camouflaged butterfly in the 2nd pic is.
Due to sheer size, it has a lot of venom and being stung requires hospital treatment. Around 40 people die every year in Japan from anaphylactic shock after being stung by these.