Nanatsu Islands were a Tropical Archipelago of Islands of varying sizes. This was one of the places in Paradise that could not be reached with a Log Pose, but only by coincidence or an Eternal Log Pose.
This was also the reason why despite being a place of breathtaking beauty, it was not so famous in the world.
There were six Islands in total, which formed a shape of a ring with an empty region of sea in the middle.
The Flora and Fauna varied too, with tall mountains and volcanos on the largest of the six Islands, Mu Island.
There was another Island of Intermediate size with mountains, Mi Island, but its temperature was unusually very cold, reaching the levels of winter Islands. And it was the only Island with no settlements on it.
The rest of the five Islands had small villages on them, and the natives made their living through fishing and agriculture.
Since it was a place where visitors rarely came and only a few ships arrived on yearly basis to buy Fruits and other Agricultural Products, it was a very peaceful place.
However, in the sky, nearly a thousand meters above the Islands, a man could be heard screaming and crying.
"Let me go!!!"
It was a haggard man in white, whose eyes had sunk in the last 10 days and who was still very weak because of the damned Sea-Stone handcuffs he was wearing on his wrists.
"Please let me go..." He pleaded. "I have lots of treasure hidden away. I will give it all to you. Just..."
"Shut up." The one who was holding him by the collar in the air coldly said, and then with a bolt of lightning, the two landed on one of the Islands in the Archipelago.
This Island was the second largest in the Archipelago, and though it was safe for people like them, it was a very dangerous place for normal people who would only be devoured by the dangerous beasts in this place.
It was also the Island filled with delicious and poisonous wild fruits, and the place they had landed at was surrounded by tall Golden Apple trees, a wild variety of normal apples, much bigger, and delicious too, but they were also very hard to digest for any normal person. Even most wild animals usually avoided these Golden Apples.
The man in white was roughly thrown on the ground, and when he managed to stand up on his knees, his already pale face lost more colour when the muzzle of a flintlock pistol pressed on his forehead.
"Goodbye, Simon the Divine." The handsome young man coldly smiled, and then everything went dark for the man in white.
The sound of a gunshot travelled far into the surroundings, which alarmed the animals in the trees that started to run and fly away in fear.
Sin put the pistol back in its holster and then used his Observation Haki to find a wild beast that was very hungry right now. And he found one not far away from his place.
Crouching down, he grabbed the wrists of the dead and then unlocked the Sea-Stone handcuffs from its wrist, grabbing them and putting them on his belt.
Over the years, he had made himself and others go through torture to earn resistance to this blatant weakness of all Devil Fruit users.
Of course, he could not utilise his Devil Fruit when he was directly in contact with it, but now, he could protect himself from letting Sea-Stone sap his energy and make him feel weak.
Picking up the body of the late pirate, Sin leisurely walked in the direction of the beast he had the lock on.
He was curiously looking around when his footsteps came to a halt and he dumbly stared at the Golden Fruit handing on a branch of a Golden Apple tree.
"Well, well, well..." He chuckled and shook his head at the same time, but then a thought crossed his mind and he shrugged.
Sin gracefully jumped up in the air, and grabbed the Pasa Pasa no Mi, plucking it off the branch, and then lightly landed on his feet.
He stored the Fruit in his coat's inner pocket and then went his way.
Several minutes later, he came across the Den of a large black Lion, which was eating a small deer, but raised its head in alarm and grave seriousness as it looked at him.
"Here." He tossed the body to the Lion, who backed off a little, but then sniffed the body, making sure that it was fresh.
Sin smiled when he watched the beast start devouring his new meal and then curiously looked inside the Den, where he had sensed the presence of Sea-Stone.
All Devil Fruit users could sense Sea-Stone from far away. It was an instinct that came with being a Devil Fruit user, and he was very sure that there was Sea-Stone Inside the cave-like Den.
The beast became a little nervous when Sin started approaching it, but relaxed once again when the man simply walked past it and entered the cave.
It was quite dark here, but Sin raised his hand and coated it with a cage of lightning, which provided enough illumination for him.
He paused when he arrived at a dead-end, but he only looked at the wall in front of him for a moment before he smashed a powerful fist on it, destroying the rocky wall that was hiding a Sea-Stone Door behind it.
"Chamber Four." He read the words written on the door in an Ancient Language and also the instructions on it.
There was a specific way this door could be opened, and only someone like him, who could read this language had a chance of not messing up.
Following the instructions, he grabbed the handle before using a lot of strength to slide the door to the left and then used more strength to slide it upwards before sliding it more to the left and then upwards again, reaching a point where he could no longer slide it upwards anymore. It was then that he finally started sliding it to the right, careful not to drop it and mess it up, and managed to open a pathway with stairs leading down into the ground.
He did not rush in but took another careful look at the path in front of him.
These stairs were made with a lot of care and were quite even, and there were clear markings on them, which might not have meant much to others, but he, who could read a lot of Ancient languages, knew that these were numbers.
Checking the side walls, searching for more instructions, he finally stepped on the stairs when he found no more clues.
All the stairs he walked by were numbered, and after a few minutes, he arrived at a point where the stairs descended in three directions.
Sin looked at the numbers carefully, as they were also meant to fool people who could read them, and after solving the riddle, he smiled and took the left staircase.
He was already over a hundred metres below the ground when he arrived inside an empty chamber with markings on the walls.
For the next two hours, Sin carefully read and deciphered the text and markings, and finally, he found himself standing in a corner, looking at the floor.
He had read the instructions and information on the walls, and his heart was a little restless right now.
Calming down, he carefully solved the puzzle by sliding a stone tile in a set pattern, which finally allowed it to be slid all the way to the left, revealing a secret pocket.
Sin stared at the object he found in the pocket, and then calmed himself down before he picked it up in his hands.
It was a key, made out of a special metal, and on it was a single marking that read "Four".
Storing the key away, he hid the pocket once again before exiting the chamber and taking the stairs.
He also checked where the two other staircases led, and as he had guessed, they led to similar chambers, with text and markings meant to trick people, but there were also some gold tiles there and some chests containing some books and gems.
Sin could not take everything with him and left with what he could carry.
On the Black Pearl, which had anchored near the largest of the six Islands, Mu Island, the crew was gathered on the deck, waiting for their Captain and all ready for the day.
"Sin!" Bonney excitedly said when a bolt of lightning landed on the ground.
"Hey!" He smiled at her and then at everyone. "Sorry for keeping you waiting." He said at them, but their attention was on the two chests he was carrying in his arms.
Hachi stepped forward and took it from him, placing them on the floor, and Sin then opened them to show them tiles of gold and gems, which made Nami scream in excitement.
"Treasure!!!"
"Bonney." Sin immediately closed the chests again before Nami could reach forward and grab something, and the Pinkette nodded to him before instructing Hachi to pick up the chests and follow her to the treasury.
Afte that, he walked into the Captain's Quarters, leaving others hanging.
"Hancock, Robin." Sin called out their names after he walked out of the Captain's Quarters, carrying a notebook.
The two girls walked over to him, and then he grabbed their waists before leaving with them in a bolt of lightning.
They arrived outside the Ruin where Sin had found the treasure, and the Black Lion was currently asleep outside the cave.
"Is this where you found the treasure?" Hancock curiously asked after she looked at the cave, but Sin did not answer her and opened the notebook to start drawing a map of the Nanatsu Islands on it.
The two girls waited for him to finish what he was doing, and they frowned at the map he had drawn.
"The Six Islands were once part of a Single Island," He informed them. "And that Island was called Soul Island. 800 years ago, something happened on the Island, it was separated into Seven parts."
"Where's the seventh Island?" Hancock frowned as she looked at the missing piece of Soul Island. "In the sea?"
"Sky." Sin shook his head, much to their surprise. "The seventh Island, the Na Island, is in the sky, right over the centre of the sea between the Six Islands."
"Did you check it?" Robin asked.
"Yes." He nodded to her.
He did go into the sky to make sure it existed before he returned to the ship.
"There is something on that Island, a special place. And on each of the Six Islands, there are secret Ruins, where a key is hidden." He took out the Key from his pocket and showed it to them. "We need to gather the rest of the five keys from the other Ruins before collecting the seventh key from the Island in the Sky to access that special place."
"What's in that place?" Robin frowned and asked.
"I am not sure. All I found from the texts inside the Ruin was that the place hides the thing responsible for what happened to the Soul Island."
The three of them glanced at each other, knowing well that it could be very dangerous, but their curiosity was already fueled, and they wanted to see that place and solve this mystery at all costs.
"Adventure Time," Hancock smirked, and the siblings laughed at her words.
"And there is still more treasure left in the Chamber inside the cave." Sin told them, making them more excited. "But, it will be just the three of us who will go to the seventh Island." He seriously said.
Both Robin and Hancock nodded to him, and they understood that they have to keep quiet about it.
If things did get out of hand, the three of them could somehow deal with it, but it would be very dangerous with the others around them.
"Go." He smiled at them. "I will bring everyone else to help carry the chests."