He who defy Gods (Arifureta X OC/Male Reader)

(Season 2) Chapter 6 Sunken Ruin of Melusine

Hajime: Considering you'd need a party of extremely skilled mages just to make it to the entrance, I'm betting this labyrinth is harder than the others.

Sora and the others steeled their resolve and stared warily out of the windshield. Just then—

Sora: Oh boy?!

Hajime: Uoooh!?

Yue: Hm!?

Aishia: Guh?!

Shea: Wawah!

Kaori: Kyaaa!

Tio: My word!?

Something hit them from the side, sending them spiraling in the other direction. Like before, the submarine flipped around in the current, but unlike the time with the magma, Hajime had countermeasures in place. The weightstone comprising the bottom of the ship's hull grew heavier, stabilizing the sub.

Shea: Ugh, I was hoping we wouldn't have to deal with this again.

Shea paled and shook her head. She hadn't enjoyed the ride out of the Grand Gruen Volcano one bit.

Hajime: Don't worry, I stabilized us already. The real question is where this current is taking us...

Hajime grimaced and looked out of the front windshield. The green glowstone headlights chased away the darkness and illuminated the cavern. From the looks of it, they were being pushed down a long tunnel. Hajime stabilized the sub, but otherwise let the current take them where it would. After a while, Hajime's alertstone picked up on a number of creatures that were glowing dark red.

Sora: Something's coming toward us.

Hajime: It's probably monsters. Nothing else glows like that.

Yue: Should I kill them?

Mana gathered in Yue's hands as she casually offered to wipe them out. Her harsh words were a stark contrast to her cute face.

Hajime: Nah, let's try out my new weapons. I wanna see how effective they are.

Hajime activated one of the mechanisms he'd added to the rear of the sub. A barrage of small torpedoes shot out of the sub's stern. He'd painted images of smiling sharks on all of them.

They had to fight against the current, so they didn't travel very fast. As a result, they ended up sitting in place, creating a minefield behind Hajime.

The monsters closed in on the minefield, and the party got a good look at them for the first time. They were shaped like flying fish, just much larger. They swam headfirst into Hajime's torpedoes.

Then, there was a huge explosion. It was so massive that it made the entire tunnel shake. The flying fish were enveloped in a cloud of frothy water. The explosion tore them apart, and chunks of flesh whipped past the submarine, blown along by the current. There had been so many of them the water was dyed red with their blood.

Hajime: Yeah, this is definitely better than before. Looks like my upgrades worked out.

Shea: Whoa. I think I just saw a dead fish's eyes staring at me.

Hajime: You probably did. I just killed a lot of them.

Kaori: I was thinking about this for a while, but the artifacts you make are completely broken, Hajime.

They ran into schools of other monster fish, but they had no problem dispatching them. As they were underwater, Sora had no way of tracking how long that went on for.

Eventually, though, Sora felt a subtle change in their circumstances. The current had carried them to a place where the walls were severely damaged. Dead eyes stared at Hajime from the cracks in the rock, and he realized the fishes he'd blown up had become stuck there.