If you look at Japanese caps from the Second World War, you will notice that they all have quite characteristic "ears" hanging from several sides. It is quite obvious that this item of clothing was invented and introduced into military uniform for a reason. If only because it is characteristic primarily of soldier's caps.
Even before the beginning of the 20th century, Japan began to expand to the mainland in Korea and China, in an attempt to expand its possessions. The Second World War for the island nation was not only the most important stage in the struggle for the Pacific Ocean, but also a new attempt to gain a foothold on the mainland. The Japanese were preparing for the new campaign very closely and thoroughly, attention was paid even to such "trifles" as the headgear of soldiers and sergeants. We are talking, of course, about the famous Japanese "eared" cap.
Why does a Japanese military headdress need such "spaniel ears"? In fact, everything is quite simple. The fact is that even during the first military campaign to the mainland, the Japanese command drew attention to the fact that it was hotter on the "mainland" than on the islands. In addition, there was a higher level of humidity, and most importantly, there were many unpleasant and even dangerous insects that the Japanese did not encounter in their homeland.
Most of the soldier's body was reliably protected from the effects of natural factors with the help of a uniform. However, there was one vulnerable area besides the faces - the soldier's neck. The practice of war on the mainland has shown that the soldiers of the Japanese army receive numerous sunburns, and also suffer massively from insect bites. This, among other things, became the cause of numerous diseases among the personnel.
Actually, to solve all these problems, they began to attach four "ears" to the caps, hanging from the back of the head and resting on the fighter's neck.
If you want to know even more interesting things, then you should definitely read about why in World War II other countries did not have their own "Katyushas".