Jax's threads weren't necessarily weak, even at just the 2-Star Opal stage. The only time they could be considered weak was when being compared to a monster or someone at the same Navi stage as him or higher.
Since he had planned on using the threads not on a monster but on something entirely different, he didn't need to worry much about them breaking off easily.
However, there was one thing to test, which he needed to do quickly.
Jax created a small thread about a handspan long and threw it into the slime. The slime's body, still moving toward Jax at a slow pace, absorbed the thread. It hung an inch deep in its gelatinous body, slowly giving off bubbles as it was corroded.
From what Jax had read, metals took longer to corrode than fabric, so he needed to first make sure that his string wouldn't be easily destroyed by it.
From his experiment, he realized that it took the string about half a minute before it was fully corroded—meaning Jax had half a minute to get into the monster's body, take the stones, and then run away.
"That should be doable."
Strings spilled out of his fingers without stopping as his body used up a significant portion of his Navi to create the threads. In the end, he had about 20 feet of threads coming from his five fingers.
Jax quickly tested the strength of one of the trees to the side and began tying up the threads around the tree, which he would use as the anchor to pull himself out.
After that, he got naked down to just his undergarments. The clothes on the outside were expensive, so he wasn't going to get them destroyed by getting the slime all over him.
The slime didn't harm human skin at all, so he was fine. He did make sure to bandage his wound well enough so that the slime couldn't get inside. He wasn't certain what would happen if it did.
Once he was ready, he grabbed the threads as tightly as he could with his right hand and waited for the slime to get closer. It slowly did, getting closer and closer.
When it was less than 10 feet away, Jax ran in as fast as he could, took a deep breath, and jumped in headfirst.
The feeling he experienced upon jumping into the slime was quite strange. It felt like jumping into a warm bath, but one that squeezed him from all sides. At the same time, it also felt like he was lying on a soft bed.
And the bed moved.
The slime slowly turned, trying to get him to stay inside it forever. If not, Jax would slowly sink into its body, falling to the ground.
Jax ignored all thoughts at once and barely opened his eyes to see where the stones were. He managed to see them, but the slime's dense body made it difficult to move his arm toward them.
There was a lot of resistance. He had to swim toward the stones to get closer, which took more than a few seconds.
Jax worried about the integrity of the thread. How long could he spend in here before the thread became too weak? He had tested it to be half a minute, but accidents happened.
Not only that, he needed to breathe soon too.
Jax moved his arms and finally managed to grab the stone. Around 15 seconds should have passed by then, enough time for him to get out. However, when he tried to pull on the string, he found himself unable to move much, if at all.
'Shit!' Jax thought as he realized the situation. There was too much friction and resistance around his body inside the slime. He couldn't pull himself out with just one arm.
He tried to move his other arm, but the resistance made it slow. And he was running out of time. Both the threads and his breath would run out at any moment now.
Jax panicked. He was about to die.
'No,' he thought. 'I can't die here. I can't…'
Navi flowed out of his body at once, surging into his right arm, strengthening it beyond the capacity of a regular person. His strength was now equal to that of a warrior—perhaps even more, considering his natural physical strength.
Then, he pulled on the thread.
His entire body lurched to the side, only halfway through, but his head was now outside the slime. He could breathe.
Jax took in the outside air and pulled out his other arm. With both arms, he pulled on the string and dragged himself out slowly before dropping to the ground.
He fell on the dry earth, the tiny splinters of wood and dirt sticking to the slimy layer that was all over him now.
Jax slowly moved further away, not letting the slime drag him back into its body. He moved to the tree and rested next to it, his back against the trunk.
The threads around the tree vanished, a portion of the Navi returning back into his body. Jax then looked at the stones in his hands with a smile on his face.
That made it a total of six stones he had gathered today. He got back up and moved away from the slime, leaving it. There was nothing for him to gain from it anymore.
As Jax left, Gemma returned to his side.
"Are you going to continue still?" she asked.
"Of course," Jax said, pulling out his knife. He used the back of it to scrape away the slimy stuff from all over his body. He didn't mind if the knife's back was corroded, since he was going to have to get another weapon soon anyway.
"I still have half my Navi left in me. If nothing else, I should be able to gather four more stones today. I can return after that."
"If you think you can, then I won't stop you," Gemma said. "Let's see how many more you can kill today."