The entire next week, Kenshin only worked. With "Formation Creation" upgraded to sixth level, huge prospects opened, dumping massive work on him. First, he reworked his sons' suits, making energy blocks more capacious and shields stronger. By his estimate, a shield could take one full-power mid-Jonin strike, but he knew average Jonin had hundreds such strikes in reserve, with far higher speed than even Ichiro could muster.
Kenshin planned adding collective shield function to their suit formations, allowing energy transfer at range to whoever needed protection, enduring far more than a single shield. But he didn't know how yet. It needed weeks of meticulous research and tests, impossible now.
He sidelined his own exo-suit upgrade, not planning to leave the haven soon. He had so much to do he sometimes forgot to eat or slept on the workshop sofa. Minimum six hours daily went to absorbing iryoninjutsu info, repeatedly amazing Hitomi with his learning ability. By her estimate, one-and-a-half months until he knew everything she did.
Another sharp problem: Kenshin needed at least ten functional katanas so his sons had edge over other shinobi.
Even as a high schooler, learning this world via laptop screen, Kenshin wondered why shinobi used tiny kunai instead of convenient, functional swords that could bisect foes. The answer was simple: cheapness and convenience.
The high cost of Katanas was not the main factor in why shinobi mostly used kunai, but it was far from insignificant. The technological capabilities of this world were at a medieval level, so mining and smelting ore, followed by forging Katanas, was a very expensive endeavor.
Such Katanas would dull and break even in battles between ordinary people, while the crossed swords of Genin would guaranteed shatter into fragments, in contrast to the somewhat sturdier kunai. The only thing that could help in this matter was fuinjutsu.
High-class fuinjutsu masters could reinforce a blade many times over, allowing high-class shinobi to shine on the battlefield. However, the stronger the shinobi, the harder it was to create a sword for him.
A Katana that a Jonin could wield cost a fortune, and was usually beyond the means of rogue shinobi. Katanas for Elite Jonin were not available for purchase. They all cost monstrous sums of money, and demand exceeded supply by hundreds of times. All because of how difficult it was to reinforce them using fuinjutsu. There were extremely few masters capable of such a feat, and the cost of several years of meticulous work by such a master was incalculable.
The fights of almost all Jonin devolved into hand-to-hand combat, since ordinary blades would break from a single swing, shattering in the air. And if they somehow reached the enemy's body, they inflicted no damage, delivering only minor discomfort, like if an ordinary person were struck by a dry twig the thickness of two straws.
This was precisely why Kenshin was fired up with the idea of arming all his sons with the strongest possible blades, boosting their combat effectiveness by 20-30%. However, even for him, this was no simple task. First and foremost, he needed swords of uniform quality, and even then, he would have to design a unique formation for each one. It would all be much simpler if these swords were stamped out at a factory from the same ore batch, to spec. But in a blacksmith's stores, the ore could be of completely varying quality, as could the force of the strikes applied to the blade itself, resulting in finished Katanas of different qualities. For an ordinary warrior, this didn't matter, but for Kenshin, whose formations had to permeate the entire structure of the sword, it was a headache.
All of Kenshin's "free" time was spent thinking about how to create a universal formation for all the swords at once. Meticulously reinforcing each Katana over several weeks was not in his plans, but he needed to order the swords now, which required no small amount of money.
In just a few days, he resumed production of ten-year and twenty-year aged wine, whose sale he could finally entrust to his older sons. In all this time, the first team had completed four missions, and all its members had grown accustomed to the outings one way or another.
Kenshin tasked his sons with finding outlets for the elite wine during their missions in various cities or villages. In his opinion, the best approach was to negotiate with caravan merchants, whom they often had to escort on assignment.
He also tasked them with finding a good blacksmith and negotiating with him for the forging of ten identical Katanas, with the condition that they all be forged from the provided ore, whose processing would once again fall on Kenshin's shoulders.
On the 244th day, Aya and Natsumi gave birth again to the Nineteenth and Twentieth. Both had low talent levels, but Kenshin wasn't upset and was glad even for sons with Chunin potential.
On the 245th day, Kasumi gave birth, presenting him with his twenty-first son, with a talent level of 31 units. This couldn't help but delight Kenshin, who couldn't wait for one of his sons to become a Jonin.
On the 248th day, Ichiro and his brothers dragged back 350 kilograms of iron ore after a mission, spending 40,000 ryō. They earned 34,000 from wine sales, so the iron purchase didn't hit the family wallet too hard, but the money issue had arisen more acutely than ever before. By Kenshin's estimates, another 100,000 would go toward paying for priority forging of the blades.
Over five missions, Team One had earned a total of 70,000 ryō, but it all went toward purchasing shinobi consumables, primarily shuriken and explosive seals. Kenshin still couldn't create analogs of explosive devices, so the seals were incredibly important. Each cost 5,000 ryō and could kill a Chunin point-blank. A Jonin took virtually no damage from the blast, and the seal's explosion was dangerous only up close to the eyes.