However, it wasn't that big of a problem.
The Nen system from Hunter x Hunter might not reach the planet-busting levels of something like Bleach, but its baseline power was still incredibly high.
Take Zushi from the Heaven's Arena arc, for example. He trained alongside the protagonist Gon and Killua.
Even though he was just starting to learn Nen, he was already far stronger than any normal person could ever hope to be — even without using special abilities.
If he hadn't had the misfortune of running into Killua, a chosen protagonist, he probably could've easily made it past the 150th floor of Heaven's Arena.
Dealing with the zombie crisis in this world should be more than enough.
The only uncertainty was that the outbreak hadn't started yet, so he couldn't confirm whether the zombies in this world were truly as weak as they appeared in the anime.
Aside from their extremely contagious nature, their individual strength was basically on goblin level.
After all, even though Highschool of the Dead was a zombie apocalypse story, the entire 12-episode series—from the beginning of the outbreak until the ending—only covered a very short amount of time. Probably less than a week.
It was impossible to know whether the zombies might start evolving if given more time, like in Resident Evil. Or whether the city might suddenly get hit by nuclear strikes.
Thankfully, there were fast-track methods for training Nen.
Vows and Limitations.
By creating strict, self-imposed rules and faithfully following them, one could achieve explosive growth in Nen power.
If normal Nen training was like doing addition, then training under Vows and Limitations was multiplication.
There were three core elements: establishing the rules, obeying them, and the severe punishment that would follow if they were broken.
Furthermore, Nen in Hunter x Hunter was heavily heart-based. Simply having the three elements wasn't enough — you had to genuinely believe in both the rules and the punishment from the bottom of your soul.
A perfect example was Kurapika, another member of the protagonist group.
Kurapika had trained in Nen for even less time than Gon and Killua.
Yet because he established extremely harsh Vows and Limitations, he reached the level of a first-rate Nen master in an incredibly short period.
He not only killed Uvogin — a Reinforcement-type who could tank cannonballs with his body — but even crippled Chrollo Lucilfer himself.
The core driving force behind Kurapika's vows was revenge against the Phantom Troupe for annihilating his clan.
Because of that, his Chain Jail could only be used on Phantom Troupe members. If he broke that restriction, the Judgment Chain wrapped around his own heart would pierce it without hesitation.
The Vows and Limitations Shuya created were partially inspired by Kurapika's, though not nearly as extreme.
The new Nen ability he gained through these vows still manifested as an old parchment scroll, but its core principle was different from "Equivalent Exchange."
While Equivalent Exchange revolved around trade, this new ability's core was contract.
After forming a contract with someone, even if the other party wasn't originally a Nen user, the power of the contract would allow them to quickly awaken their own Nen.
At the same time, Shuya would also gain the Nen ability they awakened. Moreover, any future growth in the contractor's Nen power would be reflected in Shuya as well.
As for the specific rules and punishment of these Vows and Limitations… he didn't feel the need to explain them in detail.
Shuya had modeled them directly after traditional marriage vows from his previous world.
Which meant he would be extremely selective about who received a contract.
Naturally, his top choices were the main heroines of this world — starting with Saeko Busujima standing right in front of him.
What do you mean, "my 2D wife"?
(hands on hips.jpg)
Thinking about it, Shuya couldn't help but wink at Saeko.
Although he made it sound casual, Saeko's mind was currently on the verge of exploding.
The meaning of existence… truly living…
To a girl who had spent years suppressing her true self, those words hit her like a nuke straight to the heart.
"Could it be…?"
Saeko suddenly remembered the white oak sword that had appeared out of thin air in Shuya's hand earlier.
She had seen it clearly. He hadn't pulled it from his clothes — it had materialized instantly.
Combined with everything he was saying to her…
The kendo club was one of the most popular clubs in school, and quite a few members still had chuunibyou tendencies even in high school.
You'd often see them swinging practice swords during training while shouting about "friendship," "bonds," and other cringey nonsense before charging in and going all out.
So Saeko wasn't completely unfamiliar with that kind of mindset.
But Shuya had never shown any chuunibyou behavior before. Plus, the monstrous strength he displayed during their fight made it difficult to dismiss him as delusional.
If he wasn't lying to her…
Saeko couldn't help but wonder — did some kind of hidden underworld really exist in this world? A secret side that normal people knew nothing about?
She knew better than anyone that the battle-crazed, violent impulses inside her had no place in modern society.
That was exactly why she felt so ashamed of herself.
There were many times she had wondered why she had been born in this peaceful modern era.
If she had been born during the Warring States period, maybe she could have become a legendary warrior like Minamoto no Yorimitsu.
Even if she couldn't reach that level, at least she would have been free to unleash her violent urges on the battlefield.
Instead of being forced to suppress everything like she was now.
But if there truly was a hidden world that ordinary people didn't know about… then things would be completely different.
The more she thought about it, the brighter Saeko's purple eyes became as she stared at Shuya.
"Saeko-senpai," Shuya said seriously, "are you willing to entrust your future to me?"
"I…"
Saeko started to speak, but Shuya gently cut her off before she could finish.
"There's no rush. Take this contract with you and think it over carefully. Make sure you're truly ready to accept the real side of this world."
Even though he could see Saeko becoming more and more tempted, Shuya deliberately chose not to push for an immediate answer.
It was better to explain everything clearly from the beginning and let her think it through calmly rather than rush her and risk future regret.
Of course, he had absolute confidence in Saeko.
It wasn't just because they had spent a whole year together.
It was also because, as an anime heroine, she was literally born from people's hopes and ideals.
Not to mention that even among all the dazzling female leads, Saeko still held extremely high popularity and a firm place in fans' hearts.
Otherwise, why would a smart guy like him willingly jump headfirst into such restrictive vows?
Wise men don't fall in love… unless it's with their 2D wives.