Out in the middle of the sea, the crew of the sailing vessel Oki Mariner is sailing through the South Pacific Ocean on an exploration mission. In the ship below decks, Tsuyu Asui speaks with Sirius about what they could find. This voyage is her fist on board the Oki Mariner.

Tsuyu: I wonder what we're gonna find all the way out here?

Sirius: We never know with Captain Selkie. But hopefully it won't be anything too dangerous. I'd honestly rather have this voyage be a quiet one!

Tsuyu: Is that so? 

Sirius: Don't get me wrong, Captain Selkie is a wonderful man, but he tends to be overzealous about these sort of things.

Just as Sirius said that, one of the crew members of the Oki Mariner rushed to where Tsuyu and Sirius was speaking. 

Sirius: Mick? What's wrong? 

Mick: We found something Sirius! We actually found something! Captain Selkie wants you two on the bridge! 

Mick soon led Tsuyu and Sirius to the bridge, they see Captain Selkie in the bridge with his jaw dropped. 

Sirius: You wanted to see us Captain? Captain?

Tsuyu looks out from the bridge and sees what he saw. She gestures to Sirius to look and they see a bizarre looking city with non-Euclidean geometric features. This city in particular was something no one on the ship has even seen before. 

Selkie: This....this is beautiful! I've never seen anything like it!

Sirius: But how?! This isn't supposed to be here! I've checked the map and this isn't on it!

Tsuyu: Maybe it wan't discovered until now? This has to be something no one's seen before!

Selkie: She's right Sirius! It's possible that we're the first people to find this place! We're going to check it out!

Sirius: Is that a good idea Captain? We don't know what's in there!

Tsuyu: We won't know unless we take a look!

Selkie: She's right! We're going into the city!

With that order sent, Captain Selkie assembled the crew along with Tsuyu and Sirius and made their way into the ancient city. They exited the ship and made their way to the entrance to the city. 

Selkie: Someone get those doors opened!

The crew members opened the door to reveal a vast city of ancient and almost terrifying wonder. As they walk through the city, Tsuyu begins to hear voices in her head.

Mysterious Voice: Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn........

The voice soon begins to get louder and louder to the point where Tsuyu had to stop and cradle her head. The crew stops out of concern.

Sirius: Tsu! What's wrong?!

Tsuyu: I'm......I'm hearing something......

Selkie: Are you sure? I don't hear anything. 

Tsuyu: Are you sure?! They keep getting louder! 

Sirius: If you want, you can go back to the ship. 

Tsuyu then decides to ignore what was happening and dismissed it as nothing. It seemed crazy to think that some force from within the city was speaking to her. 

Tsuyu: It's okay. I'm fine. Probably just the sight of this city. It's just so.....overwhelming. 

Selkie: If you're up to it, then we move on. 

Tsuyu: Yeah. Let's go!

The disoriented Tsuyu gets up and follows Selkie and his crew through the ancient city. As they walk, Tsuyu continues to hear that voice repeat that same verse over and over again. Soon, Sirius discovers something. 

Sirius: Captain! Look at this!

Captain Selkie and the others see a large statue of a beast of  vaguely anthropoid outline, but with an octopus-like head whose face was a mass of feelers, a scaly, rubbery-looking body, prodigious claws on hind and fore feet, and long, narrow wings behind. The others are stunned to the point of silence by the sight. 

Mick: What the fuck is that thing? 

Selkie: I don't know. It....it's not human.....that's for sure......

Tsuyu: Maybe it's a local God?

Sirius: But where's the people? It's like this place is deserted. And what's even stranger is there's no record of any god resembling this statue. It's not supposed to exist. 

Selkie was unsettled by this. It seemed that this ancient city held more sinister secrets. But they kept exploring the city. Eventually, they reach an ancient pedestal where a book was there. The cover of the book revealed it to be the Necronomicon. Tsuyu picked up the book and the voice grew the loudest it ever has.

Sirius: What is this?

Tsuyu: Some kind of ancient book. It's written in some strange language. 

Tsuyu then gave the book to Selkie, who can't make of the language written in the book. He then hands it back to Tsuyu, who continues to look through the book. But she runs into the page where she sees the chanting of what she heard. Without thinking, she decides to attempt to recite it. 

Tsuyu: Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn.......

But as she said that, the ground of the ancient city began violently shake. 

Sirius: What's going on?! 

But almost like a sudden realization brought on by a moment of blind foolishness or clear madness, Tsuyu mutters a single word.

Tsuyu: Cthulhu. 

Sirius: What?!

Tsuyu: Cthulhu has awakened.....

Soon, the pedestal soon shattered as a giant monster like hand appears. The creature that bore resemblance to the statue had come. The beast known as Cthulhu had been awakened from it's ageless slumber. It lets out a deafening and deep roar, which drove half the crew to utter madness. 

Selkie: LET'S GO! WE HAVE TO GET OUT OF HERE!!

Selkie led Tsuyu, Sirius and the remaining crew members in an attempt to escape from the beast. But as the beast gave chase, the ground began to break way. Sirius tripped and was hanging on a ledge. 

Tsuyu: Sirius! 

Tsuyu runs to where Sirius was hanging. She reaches out for her friend, but Sirius turns to see Cthulhu. The mere sight of it brought about sheer terror and crippling madness as she fell from the ledge and into the seemingly endless black pit. Many other sailors met the same fate while the rest were stomped on by Cthulhu. Selkie and Tsuyu were all that remained of the crew as Selkie began to steer the Oki Mariner away from Cthulhu. But he then turns around. 

Tsuyu: Captain Selkie! What are you doing?! 

Selkie: I'm going to kill that wretched beast! NOW DIE YOU WRETCHED EVIL THING! 

Selkie then steered the ship towards the rampaging Cthulhu and rams it into the creature's head, which bursts a foul and slushy nastiness as it lets out a terrifying wail. But as they begin to sail away, they see that the head begins to regenerate. The Oki Mariner soon escapes Cthulhu's wrath. But when they returned, Selkie had died from am unknown and mysterious circumstances while Tsuyu was driven mad by the experience. She tries to tell her story, but was laughed off as insane. When she was placed in a mental asylum, whatever sanity Tsuyu had left was no more. She spends day and night in her cell, drawing mad symbols of Cthulhu and all she saw in the city. She mutters Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn all day and night. One day after years of madness and insanity, Tsuyu commits suicide by hanging herself in her cell. But before she does so, she pens a suicide note for others to find. 

Tsuyu's Note: Now...at my end...I can fully see. My first and only voyage on board the Oki Mariner opened in me a new fear...a real fear...a fear of myself, of what I am...and of what I have always been. All that I was, is now lost. Hope? Purpose? Pleasure? All meaningless. I now walk in the shadows between worlds...and it is there I have finally glimpsed upon what lives in the dark corners of the Earth...