Lee Shin-Woo scanned the area intensely, but there weren't any monsters at the entrance, not even one. The Undead Hero who had entered the dungeon before him must have killed them all, but he wasn’t sure what manner of monsters the hero had fought that its body would be left in such a state.

"Squeak, squeak." 

"Ah, finally."

He had been absent-mindedly running through the dungeon for ten minutes without running into a single monster. Finally, he encountered one near the central area. It looked like a common house rat from Earth, but five times bigger and, in turn, many times more disgusting. He remembered then that the dungeon was referred to as the rural rat nest.

"Squeeeeak!"

"Heup..."

The rat looked weaker than Skeleton Soldiers, but at the end of the day, it was a monster of a different world; who knew what hidden abilities it would possess? Lee Shin-Woo concentrated his strength on the hand gripping the sword and cautiously took a step forward. At that moment, the Rural Rat exposed its menacingly shining front teeth and lunged at him! Lee Shin-Woo instinctually took a defensive stance and pointed his blade at his enemy. His posture was so solid that if a skeleton who knew Weapon Defense saw him, it would've been satisfied. 

[You have defeated a Lv1 Rural Rat.]

[You have received 5 Perium.]

[You have acquired a Rural Rat's rib bone.]

"..."

It takes only a single strike. How embarrassing for the rat!. Lee Shin-Woo had channeled his strength into his arm and positioned his sword to obstruct the charging rat, which had then unceremoniously skewered itself onto the blade and died. It might have something to do with the sword being a fine weapon, but judging from the amount of Perium the rat dropped, he came to an obvious conclusion. The Rural Rat was ridiculously weak even when compared to the Skeleton Soldiers! 

Lee Shin-Woo tiredly let go of the tension in his body, feeling despondent. Despite that, he picked up its rib bone and used Bone Reinforcement without thinking.

[Would you like to use the Rural Rat's rib bone to strengthen your own bones? You can reinforce your rib bones.]

"Reinforce."

[Your rib bones have been reinforced. Absorbing a portion of the Rural Rat's memories and experiences.]

[Squeak! Squeak, squeeeeak! - Rural Rat]

For a moment, Lee Shin-Woo simply stood there and debated if he should go. What would be the point of exploring this dungeon further...? However, it didn’t take long for him to get a hold of himself, and he slapped his own cheeks. The unpleasant sound of bones clashing rang through the dungeon. 

"If I can increase my stats by even one point by absorbing all of the rats’ bones, it’ll be best for me to do so. Yeah, now that I've made up my mind, I'll clear out all the dungeons nearby."

It wouldn’t do for him to get arrogant just because he had gotten a little stronger. He was only able to make this much progress without knowing magic or how to fight properly because of Bone Reinforcement!

With his mind made up, Lee Shin-Woo proceeded further into the dungeon in a calm and unhurried manner. It seems that the Undead Hero hadn’t moved past this point before its untimely demise since more and more rats were gradually emerging. He was still able to make quick work of the rats with a single strike, but he found himself having to put more and more force into his attack; the hit points of the rats were steadily increasing.

[You have reinforced your ribs. Your Endurance has increased by 1. Proficiency in Beginner Stealth has increased by 3%.]

[Beginner Stealth is now Lv3.]

[Squeeeak, squeak? - Rural rat]

It’s difficult for me to get any stat points from the level 1 Rural Rats. Is it because I’ve reached level 2? However, the Rural Rats were pretty decent in Stealth the way larvae were good at crawling. 

Oh. Realization suddenly dawned on Lee Shin-Woo. All monsters are valuable in their own way!

I can only lighten my footsteps a little bit for now, but if I improve Stealth further, it’ll help me run away from the battlefield when I need to.

In other words, the skill would be a perfect combination with Avenger. By killing the seemingly unimpressive rats, he had gained a skill with amazing potential. He would have regretted it had he turned around and left after killing the first rat.

"Squeak... Squeeeak!"

"Yeah, I'm trespassing, so why don't you try screaming a little louder?"

"Squeeeeeak!"

Rats appeared everywhere and, after taking care of them without much difficulty, he greedily absorbed their bones. As he advanced a little further, Lee Shin-Woo realized that the path was getting increasingly narrow. Conversely, there were more and more rats pouring out and scuttling about, making it difficult for him to maneuver himself. 

"Squeak!"

"Squeak!"

"Yes, yes."

He was well aware of how this dungeon intended to instill terror into the trespassers, but unfortunately for the monsters, he was able to cut down all the rats that crossed paths with his sword. Things were getting a little stuffy as the path narrowed. However, he found himself getting accustomed to Bursting Thunder as he traversed deeper into the dungeon, so he was quite pleased with the change in environments to keep things challenging for him. With that in mind, he swung his sword, its tip drawing a line from the ground toward the ceiling above him, and the Bone of Thunder Lasting surged up like lightning, brutally slicing through all the rats in the area.

"Squeak! (No!)"

"Squeak!! (It's in front...!)"

The Rural Rats' dying rattles filled the narrow passage. A side effect of reinforcing his bones with theirs was him gaining mastery over their language, and he picked up what the rats were screaming without putting in the effort, which only made him feel a tad uncomfortable. Their desperate behavior only cemented his speculation that there was something deeper within the dungeon, but he had absolutely no idea what it was. It was most likely a boss if all the webnovels and manhwa he had read were anything to go by, but...

They're showing way too much loyalty for it to be just a simple boss.

The dense swarm of rats displayed an unusual devotion to whatever they were protecting. Whenever he swung his sword, the rats filling the passage to the brim would practically kill themselves on his sword. He was no longer training his skills. It would be more accurate to call this an exercise in arm swinging. In the end, he had no choice but to opt for something different when facing an overwhelming wave of Rural Rats. He had a skill perfect for escaping from danger, and it was his best bet in dealing with such a large, dense swarm of enemies.

"Tsk... Kuaaaaaaaaaaaaahk!"

[Using Shriek of the Dead, the enemies in the entire area have fallen into a state of frenzy.] 

[Beginner Shriek of the Dead is now Lv3.]

"Squeak, squeak!?"

"Squeeeak!"

The effect was astounding! The Rural Rats, which had all rushed at him with the intent to kill, freaked out the moment they heard the shriek, and soon broke into a fratricidal war! Lee Shin-Woo shuddered when he saw the blood and flesh splattering everywhere.

This skill really isn't good for my mental health. However, it might become more amazing than any other skill with training...

He belatedly realized something obvious: Shriek of the Dead was more effective the more enemies it affected. How many rats must have been hit by the skill for it to level up immediately?!

"Squeak..."

"Squeak, squeak..."

"Well done. Now rest in peace."

He waited for the commotion to calm down before he cleaned up the horrific aftermath. After that, he gathered the rib bones without resting and inspected himself while using Bone Reinforcement.

Despite spending close to a whole day putting all his efforts into killing rats and absorbing their bones, his Endurance had only risen by 5; meanwhile, his Beginner Stealth had reached level 4. His movements had become light as a rat even though he could still see himself moving his clunky-looking body, which was a strange feeling to him.

"I've gotten a bit more familiar with Bursting Thunder, as well as with my body and the sword... Good."

Given how good Bursting Thunder was, Lee Shin-Woo could only unleash a quarter of its power by his own estimation, but at least he was able to roughly replicate the movements of the techniques. After swinging his sword in the air a few times and nodding to himself, he suddenly looked up ahead of him without knowing the reason he did it.

There was an iron gate, and it stood out from its surroundings.

I feel mana coming from within the gate, seemingly trapped. Is the gate keeping whatever is inside from escaping?

He didn't have any idea how dungeons were created, but looking at the gate, he had a feeling that they might have been set up by the goddess to protect humans from monsters. Of course, now that all the humans who were supposed to be protected by the dungeons had become undead, there was probably no point to their existence, but... He laughed bitterly and placed his hand on the gate. At that moment, a message appeared in front of him.

[Once you enter the boss room, you cannot exit until either you or the boss dies. Will you still enter?]

"Yeah."

The Goddess’s Secret Shop probably sold items that would allow one to escape from the dungeon, but he didn’t think he would need something like that right now. He wasn’t being arrogant; he had made the decision with a calm mind.

[Lv2 Rural Rat Queen]

[Lv2 Ratman]

The first thing he saw when entering the boss room were two monsters. Are the bosses normally a level higher than the other monsters in the dungeon? He couldn't tell yet. Creeping in the corner of the vast clearing was the Rat Queen, which was significantly larger than the regular Rural Rats he had encountered, and the monster standing in front of it was...well, the Ratman. Commonly called a Were-Rat, the Ratman was exponentially more powerful than Rural Rats. Lee Shin-Woo could clearly sense its much superior strength. 

"Kihik... Kihiiiiiiik! (You will not touch the queen!)"

"Kihek, Kihek, Kihek...!"

The dungeon seems to be a small kingdom where a great number of rats served their queen! By the time Lee Shin-Woo figured out the nature and whereabouts of his enemies, the battle had already begun. The Ratman charged at him with surprising speed, while the Rat Queen sprang to action and, shockingly, gave birth to more monsters!

"Squeak!" "Squeeak!"

[Lv1 Elite Rural Rat]

[Lv1 Elite Rural Rat]

[Lv1 Elite Rural Rat]

"Oh..." Lee Shin-Woo gasped in realization when he saw the newborn monsters lunging at him following Ratman’s example. The Ratman guarded the queen against trespassers, while the queen gave birth to elite monsters in order to help the Ratman drive back their enemies. Lee Shin-Woo had to recognize the amazing synergy between them given that this was a level 1 dungeon. He had expected an incredibly large rat at best.

"Ha!" 

Although the enemies he faced lived up to their status as the dungeon’s bosses, Lee Shin-Woo had fought an Undead Hero at the entrance and reached level 2. Therefore, the Ratman wasn’t that much of a challenge to him. He could read its movement no matter how fast it was. 

"Kyaaa?!"

Lee Shin-Woo charged at the Ratman with Sprint as the Ratman rushed at him, attacking him with its gleaming nails. At that moment, Lee Shin-Woo aimed for its chest and stabbed, which was the technique he was most confident in.

[Critical Hit!]

"Kyaaaaahk!"

"Squeak, squeeak!"

Lee Shin-Woo followed the most natural course of action and sent the blade through the Ratman's chest. Was that all? He had activated Sprint at the same time, thus making the blow too powerful for the Ratman to block. The ratman staggered and fell to the ground. Its dirty blood scattered in the air. 

Two of the Elite Rural Rats trailing after the Ratman collided with each other and fell. Lee Shin-Woo had the energy to spare, and he finished off the remaining, puzzled rats. 

[You have defeated a Lv1 Elite Rural Rat.]

[You have acquired 15 Perium.]

[You have acquired the Elite Rural Rat's rib bone.]

Even if he disregarded the amount of Perium the rats dropped, Lee Shin-Woo could tell that the Elite Rural Rat was stronger than the Skeleton Soldiers he had faced. Even so, it couldn’t survive a hit from him! Lee Shin-Woo collected its rib bone and shifted his attention to the Ratman. Although blood was pouring out of its chest, the Ratman bravely stood its ground. Then he saw the queen continue to give birth to rats at an even higher rate, clearly astonished by his ability. 

"Squeak, squeeak...! (I'll protect the queen no matter what...!)"

"That’s a great parting line. You may now die without regrets."

Lee Shin-Woo's red eyes sparkled. Having surveyed the now standing Ratman, he activated Sprint. If he hadn't gained the Bone of Thunder Lasting, the fight would have gone on longer, but it seemed the strength of his sword would allow him to end the battle with one more hit.

"Squeak...!"

At that moment, something surprising happened. The Ratman raised both its hands, seemingly ready to scratch him, but the next moment, all its ten nails popped out and flew towards Lee Shin-Woo. It was clear from the force with which the nails flew at him and the mana contained within that this was no ordinary attack! 

"Ugh!?"

Caught off guard by the novel method of attack, Lee Shin-Woo hurriedly swung his sword to parry the nails, and ended up with a few nails lodged into various parts of his body. Although it was painful, thankfully he had managed to prevent getting hit anywhere vital. He was certain he would’ve died once if he hadn’t learned Bursting Thunder. No, in fact, he would’ve died if he hadn’t learned and gained experience in Weapon Defense before. 

"Kyaaaa! (Kill him!)"

"Squeak!"

"Squeak!"

Seizing the opening, the Ratman pounced on Lee Shin-Woo with five Elite Rural Rats. The Ratman's hands were dripping blood, but it pushed on to kill Lee Shin-Woo at the risk of its life in order to fulfill its vow. 

"Tch... Sprint!"

Lee Shin-Woo didn't just take it. He immediately yanked out the nails restricting his movement, grit his teeth, and charged forward with Sprint. The Elite Rural Rats tried to obstruct his vision by throwing their bodies at him, but that wasn’t enough to hinder him.

[You have defeated a Lv1 Elite Rural Rat.]

[You have defeated a Lv1 Elite Rural Rat.]

"Squeak!"

"Squeak!"

"Grrraaaah!"

"Hmph!" 

The rats’ screams, the Ratman’s shriek, and Lee Shin-Woo’s battle cry clashed to create a violent chorus. In the corner, the Rat Queen was delivering Elite Rural Rats even faster in order to take care of the trespasser. However, by the time the next wave of monsters were born, the battlefield had already been wiped clean.

"Squeak... Squeak... (My... queen...!)"

[You have defeated the Lv2 Ratman.]

[You have defeated a Lv1 Elite Rural Rat.]

[You have defeated a Lv1 Elite Rural Rat.]

With one slash, Lee Shin-Woo had killed two Elite Rural Rats and the Ratman. With a nimble twist of his sword, he took care of the other Elite Rural Rats attacking him. The display of power truly evoked the image of lightning striking the earth from the sky. 

[You have defeated a Lv1 Elite Rural Rat.]

[You have defeated a Lv1 Elite Rural Rat.]

[You have defeated a Lv1 Elite Rural Rat.]

"Ggiiik...! (How...!)"

The Rat Queen howled in disbelief. Emerging victorious, Lee Shin-Woo collected the bones and the Perium on the ground in one go. Honestly, he wanted to reinforce himself with the Ratman's finger bone immediately, but right now, there was something else he had to check first, which was the ability contained in the Elite Rural Rats’ rib bones. 

"Bone Reinforcement."

[You have reinforced your rib bones. Your proficiency in Stealth has increased by 5%.]

[Squeeeeeak! - Elite Rural Rat]

"...So that's how it is."

The crack left on his ribcage by the Ratman’s nails was quickly healed. A boost to Stealth. Is that all? Nevertheless, his proficiency in Stealth had increased by 5%, which was much greater  than what the bones of regular Rural Rats granted him! Lee Shin-Woo's eyes gleamed menacingly as they settled on the Rural Rat Queen. 

"Now I'm curious how long you can keep giving birth."

"Squeak, squeak...!"

The Rural Rat Queen was struck with terror facing the wicked skeleton. Unfortunately, all she could do was give birth, and thus, under Lee Shin-Woo’s threatening gaze, she continued to deliver waves after waves of reinforcement materials—no, Elite Rural Rats.