The battle between Frankenstein and Ragar Kertia/Gejutel K. Landegre occurs when The Previous Lord asks Ragar and Gejutel to capture Frankenstein for his killings and experimentation on certain Nobles.
When Gejutel and Ragar inform the Lord that the human has not just killed the mutants but also some of the central order have not returned and others have no memories of meeting him, the Lord orders them to bring the human to him as he is worthy of the honor for gaining strength equivalent to nobles. After a knight informs them about the intruder, Gejutel and Ragar go meet Frankenstein in person.
Ragar and Gejutel introduce themselves and ask Frankenstein to accompany them to the Lord, Frankenstein is shocked to see two clan leaders but refuses to follow the Lord's orders, as he is not a noble. He questions the two nobles for attacking him and claims that the cause of mutants are the Nobles and they are the ones hurting humans.
Ragar Kertia decides to fight Frankenstein alone and overpowers him with his speed. He stabs Frankenstein but dark energy starts pouring from the wound. Frankenstein releases a dark projectile but Ragar gets a hold of it and destroys it, only for Frankenstein to aim countless dark projectiles at him. The battle continues and both of them clash with Ragar using his speed and clones, while Frankenstein fights with dark matter.
Realizing the stalemate in battle, Ragar decides to use his soul weapon, Kartas to overpower Frankenstein. But he and Gejutel are left shocked when Frankenstein summons his own soul weapon, Dark Spear. Ragar uses a Camouflage technique to mix with the environment and severely injures Frankenstein. Frankenstein manages to find Ragar and attack, but he loses more blood in the process and the Dark Spear starts to consume him. This makes him stronger but he loses all reasoning in the process and starts fighting like crazy, forcing Gejutel to intervene in order to capture him alive.
Gejutel summons his soul weapon, Legasus, to fight, as both he and Ragar try to overpower Frankenstein, to no avail. Ragar proceeds to attack while telling Gejutel that he will buy him some time to release a massive attack to defeat him in one go. Ragar uses numerous attacks while taunting Frankenstein for his lack of will at being consumed by Dark Spear. Before Frankenstein is completely consumed by Dark Spear, Gejutel launches a massive attack against Frankenstein and he falls to the ground defeated with Dark Spear, gone.
Frankenstein then has a talk about rogue nobles who make contracts that cost many people their lives. Using this confusion Frankenstein slips away and runs deep into a forest and ends up at Rai's Mansion. He goes inside with the purpose of hiding inside believing that there may be many people working there. He changes his clothes and greets Rai saying that he is the new servant there, only for Rai to tell him that those are his clothes.