But it wasn't a major issue.
The Nen system in Hunter x Hunter might not reach the world-ending scales often seen in the Big Three, but its power floor was still quite high.
Take Zushi, for instance, who trained in Nen alongside the protagonists, Gon and Killua, during the Heaven's Arena arc.
Even though he was only in the early stages of learning, someone without Nen wouldn't even compare to him, even if he didn't actively use his abilities.
If he hadn't been unlucky enough to run into a chosen protagonist like Killua, he likely would have had no trouble climbing past the 150th floor of Heaven's Arena.
In any case, it should be more than enough to deal with the zombie apocalypse in this world.
The outbreak hadn't happened yet, so he didn't know if the zombies here would be as pathetic as they were depicted in the anime.
Aside from being highly infectious, their individual strength made them fit to sit at the same table as common goblins.
After all, despite Highschool of the Dead being a zombie apocalypse anime, the entire twelve-episode run—from the start of the crisis to the end—remained unfinished.
In reality, not much time had passed in the plot; it likely hadn't even been a week.
Therefore, it was hard to guarantee whether those zombies might evolve over time, similar to those in Resident Evil.
There was also the concern of whether the city they were in would suddenly be hit by a nuclear strike.
Fortunately, there was a shortcut to training Nen.
[Vows and Restrictions]
By setting strict personal rules and adhering to them, one could achieve explosive growth in their Nen power.
If normal Nen training was addition, then training under Vows and Restrictions was multiplication.
There were three core elements: setting the rules, following the rules, and the corresponding punishment for breaking them.
Moreover, Nen in Hunter x Hunter was inherently idealistic. These three points weren't enough on their own; one had to truly believe in the rules and punishments from the bottom of their heart.
Take Kurapika, another member of the main cast in Hunter x Hunter, for example.
Kurapika practiced Nen for an even shorter time than the other two protagonists, Gon and Killua.
However, because he established extremely harsh Vows and Restrictions, his power surged to the level of a top-tier master in a very short period.
Not only did he kill Uvogin, an Enhancer from the Phantom Troupe who could tank tank shells with his bare body, but he even managed to neutralize Chrollo Lucilfer.
The core and driving force behind Kurapika's Vows and Restrictions was his desire for revenge against the Phantom Troupe, who had slaughtered his clan.
Because of this, Kurapika's Chain Jail could only be used against members of the Phantom Troupe.
If he ever violated that rule, the Judgment Chain wrapped around his heart would pierce it without hesitation.
Su Yan's Vows and Restrictions drew inspiration from Kurapika's to a certain extent, though they weren't quite as extreme.
Although his newly acquired Nen ability under the Vows and Restrictions still manifested as a piece of parchment, its core differed from Equivalent Exchange.
The core of Equivalent Exchange was trade, while the core of this new Nen ability was a contract.
Once a contract was established, even if the other party wasn't a Nen user, the power of the contract would allow them to quickly awaken their own Nen ability.
Su Yan would simultaneously gain the Nen ability awakened by the other person, and as the contractor's Nen grew through training, Su Yan would receive a corresponding boost.
As for the rules and punishments set by this particular Vow and Restriction... well, there was no need for much explanation.
Su Yan had simply modeled them after the set of rules for marriage from his previous life.
Thus, when it came to contract partners, he preferred quality over quantity.
His first choices were naturally anime heroines like the one standing before him, Saeko Busujima.
What does it mean to have a 2D waifu?
Thinking of this, Su Yan couldn't help but wink at Saeko.
Although Su Yan spoke casually, Saeko felt as if her brain was about to explode.
The value of existence, the meaning of living...
For Saeko, who had always suppressed her true self, these words were no different from dropping a nuclear bomb into her heart.
'Could it be?'
Saeko couldn't help but think of the white oak sword that had appeared out of thin air in Su Yan's hand earlier.
She had seen it clearly. He hadn't pulled it from his clothes.
It had appeared in his hand instantly.
Combined with what Su Yan had said to her...
As the leader of the Kendo Club, one of the most popular school clubs among young people, she had seen plenty of students who remained stuck in a chuunibyou phase even in high school.
During practice, it wasn't uncommon to see members holding training swords while shouting about friendship, bonds, and other nonsense.
They would then charge at their opponents with a flurry of chaotic, unskilled strikes.
Consequently, Saeko had some understanding of the chuunibyou crowd.
However, Su Yan usually didn't show any symptoms of the condition. Furthermore, considering the monstrous strength he had displayed during their duel just now...
If Su Yan wasn't fooling her...
Saeko couldn't help but wonder: did a hidden world unknown to the public truly exist?
Saeko knew all too well that her innate bloodlust and violent impulses were wrong in modern society.
Otherwise, she wouldn't feel so inferior because of them.
In fact, there were many times when she wondered why she had been born in the modern era.
If she had been born in the Sengoku period, perhaps she could have become a famous general like Minamoto no Raiko.
Even if she couldn't reach that level, that era would have at least allowed her to vent her desire for combat on the battlefield to her heart's content.
Instead, she was stuck here, unable to do anything except desperately suppress herself.
But if this world had a hidden side unknown to ordinary people, then things were different.
Thinking of this, Saeko's purple eyes grew brighter as she stared at Su Yan.
"Saeko, are you willing to entrust your future to me?" Su Yan asked her seriously.
"I..."
Saeko was about to speak, but Su Yan interrupted her.
"There's no rush, Saeko. You can take this contract back first and think carefully about whether you're ready to accept the truth of this world."
Seeing Saeko's growing interest, Su Yan was in no hurry to finalize the contract.
Rather than a contract made on impulse, it was better to be clear from the start and let her think it over calmly.
It would prevent any feelings of regret later on.
Of course, Su Yan trusted Saeko completely.
This wasn't just because they had known each other for a year.
It was also because Saeko, as an anime heroine, was an existence born from the beautiful wishes of people.
Not to mention that even among the dazzling array of anime heroines, Saeko held a high level of popularity and a prominent place.
Otherwise, knowing it was a trap, why would Su Yan create such Vows and Restrictions and jump in willingly?
A wise man doesn't fall in love—unless it's with a 2D waifu.