Miyamoto Musashi is a legendary swordsman who shines brilliantly in Japanese history. He is said to have written down the secrets of his swordsmanship and military strategy in the Book of Five Rings. However, did you know that the existing copies of the Book of Five Rings were copied by his disciples, and that there is no copy written by Musashi himself? Did Musashi really write the Book of Five Rings? And what is the true meaning of the five rings?

At the end of the Warring States period, the enemies of the samurai were not only the feudal lords who were trying to unify the country, but also the monsters who were throwing people into chaos. The monsters were not only those that lived in Japan, but also invaders from far away in space. The first to notice their existence were the ninjas who operated in the underworld using various techniques. Deciding that they needed more power in the face of such a powerful enemy, the ninjas used the secret art of summoning to request reinforcements from other planets. As a space ninja unit, they planned to eliminate the monsters and aliens. All for the sake of protecting Japan.

At the same time, Musashi became a master of swordsmanship and became unbeatable, but he wondered whether his sword was really making Japan rich and its people happy. On the contrary, he was deeply saddened by the fate of people who could not escape the negative cycle of anger and hatred, no matter how much they got their hands dirty. At that time, Musashi, who was also in contact with ninjas, heard from one of them about a plan to eliminate aliens. Musashi was deeply sympathetic to the idea, and in order to truly protect his country, he became a ninja himself and vowed to save it from the shadows.

Musashi's military strength, which earned him the respect of ninjas from other planets, quickly united the allied forces. Musashi combined extraterrestrial science and ninjutsu with his own military tactics to form the Space Ninja Union of Five, "Gorin," which is in charge of the alien annihilation plan.

Preserved foods were essential for the ninja's covert operations. One day, one of the five said, "Recently, there's been talk of a preserved food in Edo. It's said to taste good, and I'm sure it will become popular in the future." Musashi replied, "I see. In that case, we ninjas, who are originally good at making preserved foods, should set up restaurants of that kind all over the country and use them as bases for our covert operations. If it becomes popular, we can set up bases all over Japan without being found by invaders. We can also earn military funds. "What should we name it?" "Well, we wish for true peace in the world. In other words, a world where everyone can live out their lifespan in peace. We are the ones who govern longevity. Yes, that's right. Let's call it sushi, the one who governs longevity." This was the beginning of a dark page in history that is not depicted on the front stage---