By technology I am thinking of radar etc.. Not ships and such although I would be interested in ships etc as well
You cannot really ignore ships for your question. Ships is one of the places where one of the best Japanese weapons of the war was deployed, the Type 93 "Long Lance" torpedo.
The type 93 had a heavier warhead, better range, and better speed than any other torpedo in the war. It gave Japanese light fleet element devastating punch at nearly twice the reach of their allied counterparts.
Chemical and biological warfare. While it's perhaps not what you're looking for, the infamous Unit 731 experiments produced results which were quickly incorporated into the US and Soviet arsenals after the war. I'm writing on a cellphone now, but if you want I can source it up later.
Edit: Disease and Security: Natural Plagues and Biological Weapons in East Asia by Christian Enemark, pg. 88.
One way in which the Japanese were ahead of the curve to an extent was their use of something similiar to 7075 aluminum in aircraft construction. The Japanese had developed this alloy in secret in 1936 and bonded aluminum with zinc and chrome to make an aluminum that was much stronger and lighter than other aluminum alloys used by other air forces. They used 7075 for the main spar, typically the heaviest part of an aircraft. 7075 came with a variety of tradeoffs; it was more prone to corrosion over time and much more brittle than other aluminum alloys. This is part of the reason why so few Japanese warbirds can be restored to flying condition, their main spar is too corroded to be safe.
As for it being superior, that's a debatable point, however the use of 7075 is an example of the innovation that could typify the Japanese aviation industry. 7075, or variants of it, is still used within the contemporary aviation. The Allies only produced 7075 in appreciable quantities in the mid 1940s
Source
Mikesh, Robert C. Zero. Osceola, WI: Motorbooks International, 1994.
I remember reading a biography of "Chesty" Puller (easily the most famous Marine of all time) where he said that a lot of the Japanese equipment was superior to American equipment. He had a reputation for disliking "new-fangled" equipment (in one famous incident he was being shown a flame-thrower and he asked "Where do you fix the bayonet?"), so take his assessment with a grain of salt.
One thing he mentioned that I found fascinating was the Japanese use of wooden bullets in jungle warfare. Apparently they burn up or disintegrate after a couple hundred meters, but are just as effective as lead bullets within that range. He said it was very useful for preventing casualties from friendly-fire.
The Japanese produced some of the best rifles of the time period. The rifles the Imperial Army and Navy fielded were of very high manufacturing and finish quality. The Japanese government had procured a large amount of the best steel they could find to be used for rifle and other weapon production. Many people think the Arisaka rifles were inferior because of the "last ditch" Type 99's produced near the end of the war. Shortages forced the factories to drop unneeded features and components and cut back on finishing the rifles. Many of these "last ditch" rifles were what the GI's had brought home with them after the war, or had seen being used during the last months of the war, and led to their poor reputation.
Near the end of the war the Japanese had several fighter prototypes that were more advanced than the US equivalents. The A7M "Reppuu" and the J7W "Shinden" were two fighter craft that potentially could have given the US fighters a run for their money. As it was, the late-war Japanese land-based air superiority fighter, the N1K "Shiden" or "George" was superior to the US Corsairs and Hellcats that were the core of the US fighter corps.
Specifically, the Shiden's main advantage was its compactness. The Homare engine used in the Shiden and alter improved upon in both the Reppuu and Shinden was extremely compact, allowing for more space to be given to other components of the plane like armor without slowing down the plane. In effect, the Japanese were able to produce a lighter and more nimble plane that was about as armored as the slower US P-47 Thunderbolt.
The Shinden, which is one of my favorite war machines, was a plane that employed the propellers on the back of the plane rather than the front like most propeller-driven planes. The resulting configuration gave a plane that could climb to nearly 40,000 feet (in comparison, the US B-24 Superfortress had a range of around 31,000) and were a good 40-50mph faster than anything the US could put into the air at the time.
The main problem though was simply that Japan's industry, already far behind that of the US, and further wrecked by the war, could not keep up with US production, and that most of Japan's experienced pilots were dead while the US air corps continued to gain experience. Of the Reppu and the Shiden, only 9 and 2, respectively, were ever made, and the George itself only about 1000 or so planes. For comparison, the Corsair alone had 12,000 or so produced.
Source: Francillon, Japanese Aircraft of the Pacific War
Apologies, this isn't an answer but I was wondering if someone could elaborate on the Japanese "Death-Ray" I remember reading about. It had been tested on monkeys or some such?