Though the idea was tempting, Nobu doubted he would go with the path of fucking his way to the top. It was, honestly, a little too cringe. He had also basically abandoned that idea when he gave up the opportunity to become a glorified bard. Thus, while he hadn't dismissed the idea completely, it wasn't really at the top of his list of ways to increase his strength.

The most important factor behind Nobu's decision was the fact that he actually enjoyed exercising. It was a good way to relieve stress, and, while sex was often better, it actually became a chore if you had too much. There were times when he had chafed and even bruised his dick back in his previous life. This was one of the downsides to having a large penis, as, more often than not, women simply weren't prepared to deal with you.

While it varied from person to person, it took an extreme amount of arousal for a girl's vagina to expand to the point where it could accommodate more than a few inches without causing both parties discomfort. Drunk women were notoriously bad lays because of this, so, more often than not, Nobu's partners had been recreational drug users or highly experience women.

A stark contrast to the women he had interacted with in his previous life, Yui and Yuriko had both been virgins. Yuriko was a little easier to deal with but Yui's insides were basically like a vice when she climaxed. Her strength and stamina also eclipsed his by a considerable amount, so, while there was no way in hell he would never admit it, Nobu actually felt powerless even when he was the one pushing her down. It would only take one major convulsion for her to snap him like a twig, so, until his power, stamina, and durability could rival the women around him, Nobu's desire to have sex was effectively suppressed...

...

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After another delicious meal, this time prepared by Cho and Midori, Nobu allowed Kazue to give him a sponge bath before accompanying Kumiko and Kiku down the mountain. It would take a few days before the renovations were complete, but Hitomi had basically given them the go-ahead to move into his new estate if he was uncomfortable staying in the main estate.

Nobu hadn't decided whether or not he would be moving so soon, but, with nothing better to do, he decided he might as well check things out. After all, it would be much easier to make additional requests during the renovation process than after. There were quite a number of ideas he wanted to implement, first and foremost being a plumping system and a simple water heater.

In present-day Nian, the only way to enjoy a hot bath was to live near a natural hot spring or heat up water using firewood and a stove. Nobu knew the basic structure of a water heater and how to regulate steam within a high-pressure system. He might not be able to get it working on his own, but, so long as he coordinated with skilled artisans and metalworkers, they could probably fill in the blanks after a bit of trial and error. Who knows? If he found the right people, he might even be able to guide Nian into the era of steam power and regulated industrialization...

With such thoughts on his mind, Nobu allowed Kumiko to lead him to a remarkably well-concealed set of buildings hidden on the northern face of the mountain. This was basically opposite to the rest of Yumegakure, and, even to the untrained eye, Nobu could tell it was essentially a secret hideout. If he hadn't had Kumiko to guide the way, he doubted he would even be able to find it on his own.

Believing she understood her Lord's thoughts, Kumiko took it upon herself to explain, "This is one of the Yoshitsune Clan's fallback facilities. In the event of a crisis, this, and several other facilities, would serve as a last line of defense against. According to the information provided by Suzune-sama, this particular facility was designed to provide refuge to members of the Oda Clan should they need to flee the Capital."

Seeing the five-petalled flower carved into the thick defensive walls surrounding the camouflaged facility, Nobu didn't doubt Kumiko's words. Only properties and businesses belonging to the main family were allowed to use this particular symbol, the Oda Mokko. He doubted the Yoshitsune Clan would appropriate it for their own uses so it was highly likely that Kumiko's words were the truth.

"That explains why it looks like a fortress...I wonder how far into the mountain it goes...?"

Since the largest building was literally built into the side of the mountain, Nobu imagined all kinds of secret tunnels existing on the inside. After all, this was a safehouse intended to protect members of the Oda Clan. There had to be at least one escape tunnel built into it.

"If I'm not mistaken, the main residential building has seventeen rooms, a library, an armory, a main chamber, a strategy room, and three baths. If you'd like, I can request the original building plan and have it presented to you before the day's end."

Nodding his head in approval, Nobu was about to tell Kumiko to compile all the information related to his new home when Yui, and, somewhat surprisingly, Hitomi emerged from the dojo-like building located on the west side of the estate.

Before Nobu could so much as blink, Hitomi had already appeared right in front of him, a teasing smile on her face as the kunoichi around him half-lowered their heads.

"I heard you were coming and thought I would stop by. Please, allow me to show you around. There are quite a number of secrets hidden within this place. That includes a number of places that only a select few members of the Oda and Yoshitsune Clans can enter so I'll need to show you around and register your auras to prevent any mishaps from occurring."

As one of the last bastions for the Oda Clan, the fallback facility being provided to Nobu was nearly as well protected as the aforementioned's Vault of Ancestors. This was the true reason Hitomi had needed to consult with the other Elders as they would have never allowed this facility to be utilized under normal circumstances. In Hitomi's eyes, Nobu, the kunoichi around him, and the students he would train were that important...

Having no reason to refuse Hitomi's proposition, Nobu only hesitated for a brief moment, his eyes wandering to Yui before answering, "Sure. Sounds good..."

Noticing the momentary shift in Nobu's line of sight, the outermost edges of Hitomi's smile curled upward an imperceptible amount. She had viewed the passionate lovemaking between the duo the previous night, so, while she was a little disappointed by the notion that her services might not be required, she was proud of the progress Yui and Nobu had made. The more at home he felt in the Yoshitsune Clan, the better...

...

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With Hitomi leading the way, Nobu quickly discovered that Kumiko's knowledge of the estate was, quite literally, just surface material. There was a maze-like network of tunnels located beneath the main estate that connected every other building, and, so long as you knew the correct path, it was possible to follow them all the way to the base of the mountain.

More surprising than the tunnel system was the artificial reservoir that existed within. It was almost like a sewer system, but, instead of wastewater, the channels were lined with rune-embossed silver that ensured that the water running through was pure and unpolluted. It was a remarkable feat of engineering that made Nobu question whether or not his knowledge would actually have any value. Fortunately, at least according to Hitomi, the reservoir was actually a Relic from the Age of Gods. In other words, it was nearly impossible to replicate in the current era as the knowledge regarding its construction had been lost to time.

Though countless scholars had attempted to reverse engineer Relics for mass production, the most common outcome was irreversibly damaging the relic they were researching. Thus, rather than risk destroying a perfectly functional waterway, the Yoshitsune Clan had made the decision to build over and around it. This was remarkably common when large-scale Relics were involved, and, more often than not, ruins and relics from the Age of Gods served as the foundation for major cities around the world.

Prior to the incident in the forest, Nobu had always been fond of the idea of spelunking and cave crawling. He had even thought about visiting London and exploring their underground when he saw a documentary about it on Youtube. Now, being underground made him feel claustrophobic.

Fortunately, unlike a natural cave system, the tunnels beneath the fallback facility were vast and spacious. It was rumored that even humans from the Age of Gods were more than three meters in height, so, as could be expected, their constructs were much larger than modern iterations.

With an average height of five meters, the tunnels comprising the waterway had a way of making those walking through them feel small. This feeling was exacerbated by the innumerable runes and fresco-like murals lining virtually every stretch of wall.

Though it was a strange comparison to make, especially considering they were underground, Nobu likened the experience to walking through an airport terminal that had been decorated to advertise an exhibit on ancient civilizations. Some of the tunnels were large enough for dozens of people to walk side-by-side without bumping into each other, and, much like an actual airport, their uniform structure made them a nightmare to navigate.

Had he been on his own, Nobu was absolutely certain that he would have gotten irreversibly lost. The Yoshitsune Clan had gone to great lengths to ensure that anyone exploring carelessly would pay the price by laying hundreds, if not thousands of traps. This included everything from dart traps within the walls to false floor panels beneath your feet. Thus, unless you knew the correct path to take, wandering the tunnels beneath the fallback facility was, for all intents and purposes, a death sentence.

To make sure they knew the correct path, Hitomi guided Nobu, Yui, and Kumiko through the same route a total of ten times. Kumiko was the only person within Nobu's entourage that was allowed to know the actual route as she was basically his informant and adviser. As for everyone else, the area was considered off-limits unless they were helping Nobu escape. Hitomi advised him to keep it this way. After all, the tunnels weren't intended as a convenient way to get around. They were intended as a last resort to ensure his escape. The fewer the number of people who knew how to navigate them, the better.

Nobu didn't agree with Hitomi's viewpoint. Fortunately, though he might not see it that way, all of the kunoichi in his employ did. This included those who weren't allowed to know the layout. Some, particularly Kiku, believed it was better they didn't even know about the tunnels. If word got around regarding their existence, enemy forces, including those within the Yoshitsune Clan, would spare no effort to map and compromise them. This would guarantee the death of whoever the tunnels were meant to protect, so, despite Nobu's suggestion to have everyone memorize the path, the idea was unilaterally shot down by everyone present...

...

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While Nobu was busy exploring the underground on the northern face of the mountain, a youthful-looking woman with six tails and inordinately fluffy ears was offering up prayers to a shrine located beneath the main estate. This was none other than Inami, Guardian of the Yoshitsune Clan and one of the oldest beings presently within Nian. As for the shrine, who else could it be dedicated to but Inari Okami?

"Lady Inari, please lend this humble servant your guidance..."

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(A/N: It's not a secret tunnel if everyone knows about it...)