The story begins with Arcus, a member of the adventurer party "Brutal Edge," being unceremoniously kicked out by the party leader, Dan. Dan, a cruel and arrogant individual, dismisses Arcus as useless, citing his inability to participate in combat. Arcus's unique skill, <Slime>, allows him to transform into a small slime and split into up to eight copies, primarily for nighttime surveillance while Dan entertains female party members. Despite his role as a non-combatant, Arcus had fulfilled his duties, but Dan's desire for a new mage, Lyze, who can also serve as a combat-capable lookout, renders Arcus obsolete. After being physically assaulted by Dan, Arcus is filled with a burning desire for revenge and vows to become stronger.
The following morning, Arcus, determined to change his fate, decides to dedicate himself to becoming powerful. He recognizes that his current situation as a weak adventurer with a seemingly useless skill is unsustainable and that he needs to take control of his own destiny. His primary motivation is to exact revenge on Dan for his humiliation and violence. Arcus reviews his status, noting his Level 4 and the two abilities of his <Slime> skill: <Mimicry>, which allows him to transform into a slime, and <Split>, which lets him divide himself. He understands the limitations of his slime form, such as the inability to speak and reduced physical strength, but also its advantages in speed and evasion.
Arriving at the beginner-friendly grassland area, Arcus accepts a quest to defeat ten slimes. Initially feeling embarrassed to be taking such a simple quest, he soon discovers a revolutionary method for leveling up. By using <Mimicry> and then <Split> to create eight slime copies, he realizes that each copy gains experience independently. This allows him to defeat slimes eight times faster, leading to a significant experience boost. In just twenty minutes, he defeats seventeen slimes and unexpectedly levels up to Level 5. He deduces that fighting in slime form, especially with multiple copies, dramatically increases experience gain. This discovery fuels his ambition, as he believes he can now catch up to and surpass those who have wronged him.
Continuing his slime hunt, Arcus levels up to Level 6, and his <Slime> skill is enhanced. The maximum number of splits increases to twelve, further amplifying his experience gain potential. He then encounters a goblin, a more formidable monster than slimes. Despite the risk, Arcus decides to test his enhanced abilities by fighting the goblin in his twelve-split slime form. The battle is challenging, with one of his copies being destroyed. However, by utilizing hit-and-run tactics and coordinating his remaining eleven copies, Arcus manages to defeat the goblin. This victory brings him to Level 7, and his <Mimicry> ability is upgraded to allow him to transform into a "Level 2 Slime," significantly increasing his strength.
The next day, Arcus, now Level 7, enjoys a substantial increase in income from his previous day's efforts. He celebrates with a hearty breakfast and returns to the grassland area to hunt goblins. He discovers that his Level 2 slime form is considerably stronger, allowing him to defeat goblins much more efficiently. He finds that a group of four slimes can effectively take down a single goblin. This efficiency leads to another rapid level-up, reaching Level 8. With this level-up, a new ability is added to his <Slime> skill: <Auto-Pilot>, which allows his slime copies to move and fight autonomously.
With <Auto-Pilot>, Arcus can delegate the goblin hunting to his copies, allowing him to rest. While he rests, his slime copies, working autonomously, manage to defeat a staggering seventy-three goblins. This results in a massive experience gain, propelling Arcus to Level 11. His <Slime> skill further evolves, with <Mimicry> now allowing him to transform into a "Level 3 Slime" and <Split> increasing the maximum number of copies to sixteen. Realizing the immense power he has gained and the limitations of the grassland area for further leveling, Arcus contemplates venturing into more dangerous dungeons.
Meanwhile, Lyze, a noblewoman with the rare <Four Elements> skill, finds herself in the "Brutal Edge" party, which she quickly realizes is a sham. She joined to become stronger and protect others, but discovers Dan, the leader and son of a local lord, is using his family connections to artificially inflate the party's rank and is more interested in womanizing and pursuing political power than in actual adventuring. Lyze is disgusted by Dan's behavior and the superficiality of the party. When Dan attempts to force her into his harem, she refuses and is physically assaulted by him, ordered to stand guard while he and the other female members engage in their revelries. Lyze vows to never submit to such treatment.
