Where did the kamikaze's warrior code come from?

Kamikaze is a Japanese Word meaning "Divine Wind" referring to an event in the 12th Century. An enormous Mongol invasion fleet set sail for Japan from mainland Asia, but was destroyed in a storm before it could arrive at its destination. The Japanese people of the time believed that this wind was sent by the gods to protect Japan from invasion, hence its divinity.

Towards the end of the second world war, the Japanese military saw that the allies were steadfastly approaching Japan, despite enormous losses. A new unit was formed in the hoped of preventing the invasion of Japan in the same way as the 12th century " Divine Wind" hence the name.

The ethos behind the kamikaze unit, like Japanese militant nationalism in general, was based on a warped form of Bushido. A central tenet of Bushido is putting oneself at the service of one's daimyo or lord or in this case, the emperor. This ideal put duty to one's lord as paramount, even at the cost of one's own life. Dying in battle was seen as glorious, however Bushido does not countenance useless death. An argument could be made that the kamikaze pilots did not die uselessly, as they did in fact slow up the allied advance. However, in the large scheme of things the outcome of the war at that point was never in doubt, it was just a question of time before the allies reached Japan. Bushido in its strictest terms (and maybe this is just my interpretation) would not accept this death as being particularly useful, as it had no real effect on the outcome of the war and this was apparent to the Japanese military leaders at the time they created the kamikaze units. Their view of Bushido was that dying in battle was the important point, in fact the only relevant one. It didn't matter to them that whatever happened, they would lose the war and that they might be more useful to their Emperor alive to help in the postwar reconstruction.

In short:

Japanese militant nationalism exploited a traditional warrior philosophy more suited to a feudal warrior society than an industrial power engaged in total war to produce suicidal pilots whose sacrifice, though courageous, was a futile waste of their lives.