Chapter 3107

The black-haired witch said, pulling Xia De's sleeve vigorously and continuing to walk inside. After passing through various goods that were dazzling, they found a trapdoor embedded in the ground in the corner at the end of the shop:

"A little piece of knowledge: because Willandale City served as a battle fortress during the Karsenrik Unification War, almost every house, including the current Upper City, has a basement, and the basement area of some houses is larger than the ground area."

She signaled Xia De to enter the basement. Compared with the luxurious decoration on the ground, the basement was much simpler. This place looked like a warehouse for the shop, but a few sewing tables and sewing machines were also placed near the entrance.

Xia De was just about to comment on this place, then turned around and found Sylvia standing on the ground without coming down.

"The trouble is here. Recently, the girls found that after the trapdoor is closed, it can't be opened from the basement no matter what, but it can be opened normally from the ground. This situation only happens when there is only one person in the basement and they stay alone for more than ten minutes. I also checked, but didn't find any problems, so I wanted you to help take a look."

Sylvia explained from above, and Xia De nodded to show he understood:

"Alright then, you close the door. If I don't come out after twenty minutes, you help open the door from above."

The witch smiled and made an 'okay' gesture, and then really closed the door leading to the basement... Then Xia De heard the sound of locking.

"Hmm?"

Xia De blinked and shouted to the top:

"Sylvia, did you lock it?"

"Of course not, and locking it isn't trouble for you, is it?"

The girl on the ground laughed, so Xia De didn't ask anymore.

At this moment, sensing the surroundings, there were indeed no traces of any elements. He went to touch the wall again, and then checked the ceiling and floor of the basement, and there were no problems either.

"Enhanced Space Perception."

Everything around was ordinary, so Xia De had no choice but to honestly wait for ten minutes to pass. Although he didn't like rummaging through other people's things, he still walked around the basement with the remaining time.

Not only fabrics and materials, but there were also some spare art paintings and decorations in the warehouse.

Xia De even saw a strange pencil sketch in the very back of the warehouse -

A bottle has a hole at the bottom, the neck of the bottle extends, then twists into the interior of the bottle, and finally connects to the hole at the bottom of the bottle.

This is not a real object. The 'bottle' has no 'edge', the surface will not end, and a fly can fly directly from the inside of the bottle to the outside without passing through the surface, meaning it has no inside or outside.

Perhaps in the eyes of most people in this world, this is just a strange painting with a sense of art, but the outsider recognized what it was:

"Klein bottle."

This is what the outsider's hometown calls this kind of existence. Simply put, this is an object in four-dimensional space. Its structure and properties cannot be fully realized in three-dimensional space, so it cannot be truly created in the material world.

A paper strip can be twisted and connected to create a 'Mobius strip', where the ring has no front or back. But the current three-dimensional twisting cannot be truly reproduced, and can only be simply summarized as the bottle having no inside or outside.

This painting was created by Sylvia, because there is that witch's fancy letter signature in the lower right corner of the sketch. Xia De felt that Sylvia deliberately put it here for him to see. The witch lady was just short of making this painting glow to remind Xia De that this was an important item.

However, this painting is also an ordinary item, which Xia De is very sure of.

After ten minutes ended, nothing strange happened in the basement. Xia De walked up the steps and took the initiative to open the basement door. After finding that it was indeed locked, he tapped it with his finger:

"Key of the Door."

With a click, the lock on the outside fell off automatically. Now that he has promoted to a high ring, he can even use this strange art just by touching the door without directly touching the lock.

Xia De, who was very curious about what happened here, opened the door upward, and then saw that what was outside was not 'Exquisite Clothworks', but a mud passage sloping upward.

"This... Enhanced Space Perception."

After using the strange art, he frowned suddenly. The strange art was successfully activated, but he couldn't understand what the spatial structure he saw meant. What he probed was not a complex maze or a passage so long that the boundaries couldn't be known. He saw it but couldn't understand it:

"So, space perception abilities have this kind of nemesis."

After testing it slightly, Xia De drilled into the mud passage in front of him. After a journey that wasn't long, the faint light of the silver moon illuminated a red brick wall at the end of the curved passage. And after he opened the brick wall with 'Fossil to Mud', what he saw was the back of a huge drawing board.

After pushing the drawing board away and leaving the passage, he returned to the basement of the shop. And that sketch standing by the wall just now was, of course, Sylvia's handmade sketch.

The clues were too obvious. Xia De didn't even need to repeatedly leave marks to test, and understood the principle of 'spatial circulation'.

General spatial circulation is to distort the position of space to achieve 'head-to-tail connection' like a circle. And although the appearance of what was encountered this time looked the same, it was actually the 'Klein bottle' left by Sylvia.

Of course, Xia De doesn't know what it's called in this world.

"Then how should it be broken?"

Because he couldn't understand the spatial structure of the outside world, 'Lagley's Jump' couldn't jump out of here either; and since this wasn't a lock, just a special spatial phenomenon, 'Key of the Door' naturally didn't work either.

"Space Stabilization Halo!"

He stepped on the ground with his right foot, but nothing happened around him.

Xia De continued to think. In fact, he didn't know much about the so-called 'Klein bottle', just having read some theoretical knowledge.

'Klein bottle' involves the concept of 'no boundary'. If this place is really constructed according to this concept, then in the outsider's superficial understanding, the key to breaking this kind of space lies in understanding the fluidity, continuity, and dimensional interaction of space.

Theoretically, this requires constructing a countermeasure through several key mathematical and topological concepts. But in fact, using superficial methods, it is -

"Cut the boundaryless space, flip and twist it, and then re-stitch it" or "Although space has a complex structure as a whole, it still looks like normal space locally, so it can be transformed into a space with boundaries and orientation through spatial folding and local mapping transformation."

Of course, although Xia De knew the theory, he couldn't perform such complex operations.

The sound of a flute rang out, and red butterflies emerged from the void. The butterfly swarm flew around Xia De for a week before landing on the ground and turning into the sisters holding hands:

"Sir, you really thought of us. A little hint - that witch said in advance that you can only ask us for help once tonight!"

Grace said with a smile, not surprised at all by being summoned, and the power of the Space Chosen One could obviously penetrate the special space Xia De was currently in at will.

Helen in the black dress reached out and held Xia De's hand, also asking with a smile:

"Sir, then do you need us to help you escape from here?"

Xia De shook his head, but he already knew that this matter was indeed Sylvia's own handiwork rather than 'trouble':

"No need to take me out directly. Can you perform spatial cutting, and then reshape the space after twisting it?"

He pointed to the sketch behind him and explained the current spatial environment to the sisters in detail. Grace and Helen listened with a smile, then nodded quickly and said together:

"You passed!"

Grace didn't know where she took out a box and handed it to Xia De, then pointed to the direction of the basement door:

"Space has been restored, sir. Now you can leave, have a good time tonight!"

Then they turned into a butterfly swarm again, circled Xia De for a week, and disappeared. After Xia De opened the box in his hand, he found a piece of silk cloth inside, on which a complex and unique ritual was recorded in black ink:

【Spatial Ritual · Bottle of No Boundary: Construct a unique circulating space. If you cannot understand the structure of the circulating space, you cannot leave the circulating space by the usual methods of breaking the circulating space.】

The silk cloth recorded all the details of this ritual as well as the design ideas and thoughts. This ritual seemed to be created by Sylvia herself. If she were given more time, she might be able to turn the ritual directly into her own strange art, and perhaps eventually construct a unique spatial maze lock:

"Really amazing."

The silk cloth in Xia De's hand can be considered Sylvia's painstaking effort. This kind of precious knowledge can only be taught after testing even for apprentices, and Sylvia gave it to Xia De so easily:

"Is this considered a clearance reward?"

After he put away the silk cloth, he successfully returned from the basement entrance to the ground part of 'Exquisite Clothworks'.

At this time, although the lights in the shop were still on, Sylvia was no longer here. However, some goods were cleared out, and a changing mannequin wearing a gorgeous noble lady's dress stood in the back part of the shop selling private fabrics.

As soon as Xia De appeared, the black ball in the mannequin's hand was thrown at Xia De. Xia De instinctively raised his hand to block it, then felt that he had blocked a ball, and the force was not great.

After the ball touched his palm, it immediately rebounded toward the mannequin. After a complex golden spiral shield flashed in front of the mannequin, the 'ball' was bounced back to Xia De again. This time he still chose to block it with his hand, and clearly felt that the power of the ball had increased a lot.

The 'ball' bounced back to the mannequin again. After touching the golden spiral shield that flashed in front of the mannequin for the second time, the power of the 'ball' that bounced back for the third time was already so great that Xia De felt a little pain.

(End of chapter)