My grandfather was in the US Army and fought on New Guinea and in the Philippines. He didn't like to talk about the war much, but the one time he opened up he said something about soldiers being hidden high in trees. This seems wildly impractical but I recall him sounding very impressed by it. I'm sixteen years too late to ask for clarification now and his memory wasn't always the best, so: Was this a thing? If so why and how effective was it?
I've read many accounts of this. The basic notion was to give a sniper a wide field of fire in dense terrain, as well as the ability to observe.
Accounts of the Australian attacks on Buna in northern New Guinea cite many cases of snipers being hidden high in trees, to the extent that tanks co-operating with the infantry developed specific tactics to deal with it (Bradley, Hell's Battlefield).
British and Commonwealth troops fighting in the Admin Box (see Holland, Burma 44) dealt with troops in trees.
The Japanese army was weak in support weapons, and had to do much fighting with basic infantry squads. Japanese troops were expected to perform sacrificial missions. Given the situation and resources at hand, a few men strung up in trees, camouflaged, could hold up an advance for hours or even days, taking a steady toll of officers, radio operators and such.