Arai Shakkū is a secondary supporting character in Rurouni Kenshin. A blacksmith and creator of weapons in the ranks of the Isshin Shishi and the times of the Bakumatsu, Shakku was the mastermind behind the creation of many swords of his time, including Himura Kenshin's Sakabatou.
Throughout the series, it's been said that Arai was both notorious and famous for being an eccentric, yet prodigious and creative genius, having fashioned many unique swords of different function and design. However, many of his swords, no matter how aesthetically pleasing and inspiring they were at the naked eye, were in fact tools of death more gruesome and destructive than any normal weapon made. Out of many, some of these were:
- Renbatō - This weapon was a set of twin katana, able to be connected at the hilt and form a parallel double bladed sword. Theoretically, the blade's dynamics would see it leave behind such damage, that the wounds inflicted would be near impossible to heal and mend properly.
- Hakujin no Tachi- A katana whose process was set around the idea of thinning the blade for the edge to become extremely thin and extensive to see how long the edge can get; as a result, the sword is whip-like and can be controlled to move even while swung.
- Mugenjin- A katana specially designed to counter the inevitable wear and tear all blades come to see in usage. With a special finishing polish and its edge fashioned to chip away in a serrated fashion when it sees usage, these features also come to use the fat and fluids of those slain by the edge of this blade to ensure its durability, and as a side result, friction allows these seeped fats to ignite into flame.
However, as the violent years of the Bakumatsu were to come to a close, Arai soon came to design and forge a blade that would mark the end of his career. Many of his peers were astonished as if he had gone mad, and Arai would come to create the Sakabatou, a reversed bladed katana, and the ultimate testament for the true reason why he forged deadly weapons. Made as a katana whose edge could not kill with ease, Arai made it in mind as a holy sword to be offered to honor the kami of Japan and the peace the new era of the Meiji would represent. This would be one of his final, and notable works, to be made before his late passing.
Arai was a swordsmith of notable fame during the Bakumatsu. In order to help create the new era, where people could live in peace and freedom, Arai used his talents to create many weapons of creativity and design, along with them bearing his school's praised quality and worksmanship.
However, even as he was an artist, the weapons he made were still as what they were made to be, being weapons designed to slay and kill, and some of his unique masterpieces were weapons whose construction ensured a gruesome and horrific death, all in a time of war and where the world was in a turbulence that could see no end. But even as this dark truth was still fresh within his mind, and even with all of its consequences, to even where making a new weapon pained his heart in knowledge of this truth, Arai still believed in how it would be those who wielded his masterpieces, not his weapons, that would build the new era, and so, still persevered and lived each day working his talents.
In league with the Isshin Shishi, one acquaintance of his was the skilled Himura Kenshin, a hitokiri of the legendary Hiten Mitsurugi-ryū school who used his pieces in his work. But during the early stages of the Toba-Fushimi battle of the Boshin Wars, Arai saw his friend changed and to leave its ranks on a journey to help the unfortunate throughout Japan without bloodshed. Although still faithful in his ideals, Arai was still skeptical of how a world could exist without the need for necessary violence. Seeing Kenshin was to go about his journey without exercising self defense and the need to pacify those that would not share his friend's ideals, Arai reminded Kenshin, that despite the pain of being a swordsman suffered, he could not give up the path which he walked. Tossing him the kageuchi of the Sakabatou, Shakku told him to uphold his ideals with that "piece of scrap metal", and of how hard of a journey it would be with such ideals in the time to come; should it have broke on his wandering, Shakkū wanted him to return and see him again.
Over the new era of the Meiji, Arai would possibly see that Kenshin was right, and that the times have changed, in that tools of killing would not be needed in the years to come. Unfortunately, Shakkū and Kenshin would not come to meet again, as he would pass on during the second year of the Meiji, in 1870.
Shakkū would be succeeded by his son, Arai Seikū. Although skilled and trained rigorously, he hated his father and the dark reputation that loomed over his family, and chose to abandon the trade of sword making, instead manufacturing kitchen ware and knives.
As the great threat of Shishio Makoto loomed over Japan, and how one of his thugs of the elite Juppongatana, Cho the Swordhunter, came to threaten his grandson Arai Iori in demand for his final masterpiece, Seikū would come to learn the truth, that Shakkū hated having to manufacture weapons of murder and only did so, so that future generations could enjoy an era of peace, under the arms of those that would guide and see the future to it. It was revealed that Shakkū's final sword created was the principal forge of the Sakabatō, and the offering of a holy sword to the Hakusan Shrine, in honor to the Meiji and the gods of Japan to ensure that the peace would last for the generations to come.
Although he passed on, Himura Kenshin fulfilled his promise to return to Kyoto, and was personally given Arai Shakkū's final work by his son (Arai Seikū) and his family to fulfill his mission of saving the nation from Shishio's tyrannical grasp; even if Arai Shakkū would still be alive then, there would be no doubt that he would fulfill his end of the bargain, and give him the principle forge.
The Sakabato would then be passed down to Myōjin Yahiko, five years later.