#present era

Chapter #90: Fushi pushes themselves worryingly hard without taking a break before the battle even starts.

It makes sense. An immortal doesn’t need food or rest to live (never mind that the lack of both those things clearly made a negative impact on Fushi’s ability to function, just like an ordinary person who pulled an all-nighter). Fushi’s comfort is obviously worth less than people’s lives. But this choice is built on a very big assumption that Fushi makes: they and they alone are responsible for saving Renril.

Before coming to Renril, Fushi had made an enormous amount of progress training their abilities, so much so that the efforts of everyone around them now seemed meaningless in comparison. We first saw this when Bon and Kahaku came to visit them, and realized that Fushi could now defeat nokkers from a distance with little to no effort.

Chapter #85: Fushi defeats a nokker without even moving, to Bon and Kahaku's unease.

Fushi stopped being bound by human limitations, and started conceptualizing themselves as a part of everything around them. This change in perspective combined with their pre-existing belief that they have to atone for being alive—plus Bon’s encouragement that they have unique gifts—created a sort of double standard. Fushi expects too much of themselves and too little of everyone else: in short, it’s a god complex.

Chapter #88: Fushi tells Bon that getting Renril's soldiers to cooperate is unnecessary.

From Fushi’s dismissive attitude towards other people in Renril, it’s apparent that they’ve begun seeing everyone as distractions. Almost like insects, humans are small enough to no longer be significant.

Chapter #93: Fushi notices how tiny humanity now feels.

But once the battle starts, it quickly becomes clear that Fushi’s not as all-powerful as they need to be. They still get exhausted like a normal person, and the lack of sleep starts to affect their ability to focus pretty quickly. People work more efficiently when they rest regularly, and Fushi is no exception—taking a break at any point during the battle would have been the wisest course of action. Yes, it would have probably cost people their lives, but they were already passing out unexpectedly, throwing up, getting nosebleeds, and at one point tried to give up completely. People ended up dying anyways.

Fushi even had immortal allies that they should have been able to rely on when necessary. But Bon—leading Kai, Hairo, and Messar—insisted that they push through this fight because he believed that in the long run, he was preserving Fushi’s humanity for them. As the one who gave Fushi the will to live again, Bon’s words were enough to convince them they were doing the right thing… up to a certain point.

Chapter #105: Fushi responds after Bon promises to tell them the truth once the battle is over.

There was potential for Fushi’s allies—Kai, Hairo, Messar, even Cam and the other Renril soldiers—to convince them to rely on other people a little bit more during the battle. And maybe, after the nokkers were gone for good, Fushi could have easily settled back into their human lifestyle if everything had gone as Bon planned it. But Kahaku’s unpredictable actions ended up causing permanent damage.

Chapter #106: Fushi admits to Kahaku that they want to rest.

Fushi placed their trust in Kahaku, and the result was them almost dying and Kahaku killing himself. Kahaku unintentionally ended up becoming a very good reason why Fushi shouldn’t rely on their friends, ever—ironic, considering he was trying to prove the opposite. That’s going to have a palpable effect on their decisions from now on.

The Present Era

Chapter #115: Fushi reflects on why they want to create a peaceful world.

So with that, we’re caught up to the present era: the world that Fushi spent five hundred years perfecting. Currently, Fushi is banking on this era being so peaceful that playing god is no longer necessary. Their plan was to work until every last nokker was eradicated, and only then would they allow themselves to live a normal life with their friends. Five hundred years of penance for an eternity of happiness is a fair deal to make, no? Fushi is supposed to be able to live as a normal human now.

But what happens if it turns out that the present era isn’t as peaceful as it looks? What will Fushi do if something goes wrong? Well, Fushi’s promise was to make this world truly peaceful. So they have to fix it.

Fushi already refused their friends’ help five hundred years ago when they entered into their deep sleep—and they only resurrected their friends because they were absolutely sure that there was no more danger. Why would they put their friends in danger again by relying on them now? From Fushi’s perspective, the only choice is to cover up their mistakes before anyone else finds out.

The exception is Bon, who Fushi continues to use as their confidant. He’s in a slightly different position from the rest of their friends, as the one who first started them on their path towards godhood. Fushi’s able to trust him as an advisor in a way that they can’t trust anyone else—because they’re sure he’s going to continue enabling them.

So, that’s the main reason why Fushi lies: they tell themselves it’s an "act of selflessness." In each case, it would trouble their friends and others if they knew the truth about what was going on, so they tell some white lies.

There’s a quote from Fushi in the present era trying to comfort Mizuha (the deuteragonist of the present era) after she explains something her mom did to upset her that I think summarizes it nicely:

Chapter #125

Fushi is speaking from their own experience here. Later in this very same scene, they tell Mizuha a comforting lie about her ancestor being a good person and leading a happy life. This is confirmation that they think lying is a kindness, and that it’s motivated by care for the person in question.

The thing to remember whenever Fushi lies is that they think they’re doing it for someone else. Their lies often have the immediate benefit of not making the other person sad; Fushi is only delaying their eventual disappointment.

But here’s the thing: Fushi’s not protecting their friends for selfless reasons. They’re doing it because they’ll be hurt by the truth, too. Shielding their friends with lies is the same as putting a band-aid on top of a cut without treating it. It doesn’t solve the problem, it just covers it up so Fushi doesn’t have to think about it. As Mizuha so bluntly points out during her conversation with Fushi:

Chapter #125

In Mizuha’s case, she believes lying is a sign that her mom doesn’t actually care about her and is just trying to protect herself. I think the truth is somewhere in the middle: Fushi and Mizuha’s mom do indeed both lie to people because they care about them. It’s just that they care more about those people being safe than about their autonomy. Just like in Renril, Fushi still views the people around them as weak and incapable. They choose what they think will make their friends happy, but deny them the chance to make the choice themselves.

The fact is no matter how powerful they are, Fushi isn’t a god. Even the Beholder, the closest thing To Your Eternity has to an omnipotent being, cannot control people’s thoughts and actions.

Chapter #32: The Beholder admits to Fushi that he could defeat the nokkers, then explains why he can't permanently stop their attacks: they have free will.

So Fushi can't make everybody happy, or make a truly peaceful world. Because in order to do that, they would need to be able to control people's hearts. The closest they can get is to control what people know. This is a conflict that is central to the present era and the final arc of the story. I think a lot of the people who think Fushi should keep powering up like the protagonist of a shounen battle manga miss this.

I would be remiss if I didn’t also mention how similar Fushi’s struggle to adapt to the present era is to people who’ve left abusive or otherwise dangerous situations. When someone develops a coping mechanism to handle a specific problem, it doesn’t just disappear once they get out. It sticks around, and it doesn’t function like it did originally, because it’s responding to different stimuli. Think of a boat: when traversing the water, a boat is handy and necessary for your survival. If there's a flood, you need a boat to get around. But when the water level's gone down and you're trying to get somewhere by land, the boat is no longer helpful. It isn't just useless; having to drag it around everywhere also slows your progress (my friend was the one to suggest this analogy, and I find it very apt).

Fushi is in a completely new environment, but they’re still acting like they did in the previous era. It was the safe choice for Fushi to not rely on others when they were in a situation where nokkers would kill their friends. Now that they can resurrect people and the nokkers are no longer an issue,* it’s harmful to their new, peaceful life. Fushi has no good reason to not just tell their friends the truth—in fact, they’re denying themselves allies (or even just a sorely needed reality check). Worst case scenario, it could even damage their relationship with their friends if they find out Fushi's been lying. This behavior is a carry-over from the previous era, but it’s now a hindrance to Fushi instead of a help: it’s maladaptive. 

*Maybe.

Immediately jumping down like that is a bit of an overreaction, no? Fushi has seen Hayase's reincarnations six times already. It's such old news that they didn't even bother getting out of bed when they met Kahaku for the first time (by the way, the frame of him in the OP is from that exact scene, haha). It shouldn't be a surprise to see that the lineage is still alive and kicking five hundred years later.

But... Fushi is surprised. For some reason. They actually have to get close up to Mizuha's face and stare at her in silence long enough to make it awkward before they can finally believe it (in the manga at least, in the anime they're an appropriate distance—though that's just because Mizuha immediately backs away when they try to get closer, ahahaha).

This isn't just a mild "oh, so Kahaku chose to reincarnate?" level of surprise. This is so disbelieving that they need to actually double-check to make sure. And their initial reaction after verifying Mizuha's identity wasn't to smile and ask how she was doing. It was this face:

When asked what they were going to do about Kahaku at the end of the Renril arc, Fushi said this—

—right before they went under. There was no time to go meet with Kahaku before the timeskip. They didn't even try, even though at this point they had already decided on going to sleep until they eradicated all the knockers. Isn't that indirectly admitting that they were planning on having the conversation after they woke back up?

Keep in mind Fushi hasn't actually seen any of their friends yet, apart from March. They've just assumed that they're all doing fine—and that they all chose to wait those five hundred years for the world to change. So, within the story's timeline it's entirely possible Fushi just assumed they had resurrected Kahaku and didn't notice otherwise until running into Mizuha. And really, why would they have to worry about the guy who said he would always be by their side?

I repeat, why would they have to worry about this guy? There's literally nothing to worry about. It's fine. Just trust him. It's probably fine.

When you look at it that way, running into Mizuha by pure coincidence was probably kind of a gut-punch. Anime Fushi genuinely sounded happy that she was happy with nothing else getting in the way but at the risk of sounding like a conspiracy theorist I 110% believe manga Fushi had... mixed emotions. Look at these expressions:

There's a hint of melancholy in there. Kahaku has been granted the posthumous title of "someone Fushi used to know." That's probably the most tactful thing they could have said, but still. Wow.

I guess whether or not Fushi actually tried to resurrect Kahaku like the rest of their friends is a little debatable. Maybe they had just hadn't gotten around to bringing him back yet. But they are in fact so shocked at seeing Mizuha's face that I would completely believe that Kahaku's empty body is decomposing in Yanome somewhere. Good angst material, if anyone wants to take that and run with it. Hell, I might do it myself.