I do not own either Oregairu or Re:Zero

"What the ...?"

Where the hell was he?

Hikigaya Hachiman had just unwillingly stepped out of his comfortable home to get some stuff. He had taken some extra time to get a can of his beloved max coffee to the grocery bag. And now he was on a sidewalk near a fountain with just a blink of his eyes. No glowing magic circle, no sexy goddess in skimpy outfit offering him power to do something, nothing at all. The whole experience was just as unnoticeable as himself.

The road in front of him that was empty, was now bustling with what was either demi-humans or humans with scarily realistic cosplays. As scary as that was, if they weren't demi-humans but people with such realistic masks, then that was even more scary. There was no doubt about it in his mind as he realized what just happened.

"Isekai"

The wonder from Zaimokuza, Hiratsuka-sensei as well as his own eight grader syndrome was inevitable. He was in a dream like world that most likely had magic and different sentient species.

But it only lasted for a second. Then came horror of leaving the familiar and peaceful Chiba without notice for a dangerous place. He was no longer the optimistic child who wanted to live in a fantasy world of swords and magic.

He was hit with a panic-attack that made it hard to breathe. He wanted to do nothing more than just find an alleyway to fold into himself and wallow in his misery.

He would have done just that but noticing a few looks towards himself stopped his panic. What he hated more than anything was pity, specially from strangers. He took a deep breath and focused on what he should do.

First he made sure that his foot hadn't moved from the spot. Then he took out the max-coffee from his grocery bag and started drinking it. As much as he hated losing any of it, he deliberately dropped some of it on the ground. This was the only way he could think of to mark the spot without being noticeable. Then he moved around that spot a few times in different ways before giving up with a sigh and sitting down at the fountain a few steps away.

He was holding hope, no matter how unlikely, that he had moved through an accidental dimensional gate and hence the location of his transportation might be a way to return but it failed. Even if his theory was true, if the gates location was not fixed then it was a bust.

He stared hard at the spot with wet marks from drops of his coffee for memorizing the spot in relation to the fountain, just in case it became useful in the future. There was always a chance that the location was right but the gate appeared and disappeared with some pattern in time. He considered marking the spot with a stone by scratching on the pavement but damaging public property so publicly was not a smart thing to do.

Then he looked around for any special looking buildings as reference for the fountain itself which was unlikely to be unique in such a big city. The architecture was surprisingly modern with only a few medieval buildings, something that contrasted sharply with the weird lizard drawn carriages used for transport. He saw a big palace like castle in the distance which confirmed that it was a capital. A noble was unlikely to have such an elaborate castle. It must belong to the royalty of this country.

Sitting down with noise of the crowd and the sound of water falling from the fountain as his background music, he thought about his objectives. His first thought was to return home no matter what or how long it took.

But was that really the case? He imagined returning ten years after his disappearance. Komachi who would have cried so much at that time initially, would have already gotten over it by then until he disrupts her life again. Same for everyone else who took his request for genuine seriously.

No, that would be unforgivable. He considered various ways to mitigate it like he might appear at the time of his disappearance or some kind of time dilation but he did not consider himself that lucky. Any of these things would mean someone is providing energy to run the world for him by ignoring the laws of physics which was ridiculously optimistic. So he looked at the sun and guessed by his internal clock that time for the planets rotation is around the same here.

"Six months."

He quietly but resolutely told himself that if he couldn't return within six months, he would give up on returning. Until then, he would do everything in his power including risking his life to return at any cost.

A.N - Hachiman of this story is from between season two and season three. Which is to say that his connections with all the Oregairu characters have been established but he isn't dating Yukino yet. This is necessary for him to have any chance of romance in this world as he is not the type to just move on without his partner.

For those who know Re:Zero but don't know Oregairu, Hachiman is somewhat similar like both of them having mean eyes and yet very different from Natsuki Subaru. Physically Hachiman is weaker than Subaru who works out at home (no 70 Kilograms grip strength), but has a lot more stamina from cycling and really good hand-eye coordination and reaction time in sports that increases his livability in this world full of monstrous people by a lot.

He is much smarter with the observation ability of a detective but also very pessimistic. Subaru has a strong will but Hachiman has strong spite. He runs more on sheer pettiness as a fuel than love. Subaru hates himself but Hachiman only does that when he puts generalized labels and expectations on others and those are off the mark.