The story revolves around the main protagonist Cadis Etrama Di Raizel and his loyal servant Frankenstein along with the human friends they meet as they oppose a secret human organization and while at the same time, uncovering more about Rai's past. The main setting for the story is Korea.
Awakening in a New World Arc
The Awakening in a New World Arc is the first arc of the story. It spans from chapters 1 to 92 in the manga. It revolves around Raizel's awakening from his 820-year slumber and his initial struggle to acclimatize himself with the modern world (with frequent aid from Frankenstein). This arc also features the Organization's attempts to locate the casket, which unbeknownst to them, was the very same coffin that Rai had awakened from. The arc introduces some of the main characters of the story which includes Rai, Frankenstein, M-21, Shinwoo, Ik-Han, Yuna, and others.
The Human World Arc
The Visitor Arc
The DA-5 Arc is the second arc of the manga and spans from chapters 93 to 154. It deals with the weapon specialized team, known as DA-5 and their creator Dr. Arith who are investigating Dr. Crombel after his recent promotion to the rank of Union Elder. They eventually get entangled with the main characters as the story progresses. More of the main characters are introduced such as Regis, Seira, Tao, and Takeo.
Dr. Aris Arc
The Lukedonia Arc is the third arc of the manga and spans from chapters 155 to 200. It deals with Rai and Frankenstein's return to Lukedonia (Rai's homeland and the home to the Noble race) along with Regis and the RK-4, due to his concern of Gejutel hiding Rai's true identity from the Lord. The hierarchy of the Nobles is thoroughly explained in the arc.
This is the first arc of season 4 which features the introduction of the KSA. It features two new mysterious teachers arriving at Yeran. It is later revealed that they are not what they seemed.
Cerberus Arc is the second arc of season 4. Here, Cerberus members arrive and fight ultimately, die. Two were killed by Yuri who was acting as a double agent, working for the 12th Union Elder and later on revealed that he was working for Dr. Crombell. Yuri was tasked to gain a sample of a KSA body and in the end he killed Yuizi and Lutai.
The 12th Elder Arc
The arc features the arrival and death of the 12th Union Elder, It also introduces another Union Elder, a traitorous clan leader, Roctis Kravei. It offers more insight into Rai's duties and powers as the Noblesse and finally, the group RK-4 gains two new members and now bears the title of RK-5.
This arc features the past meeting of Rai and Frankenstein. It also brings back an old face in the present city: M-24. He is shown as a fugitive running away from Union experiments who finds shelter in Frankenstein's residence.
On this second arc, M-24 is revealed to be one of Dr. Crombel's spy-assassins who carries out a secret mission within Frankenstein's residence. The household engage in a clash with two new elders. Tao and Takeo end up in life-threatening situation where Rai has to step in to rescue them, rendering himself more jeopardized.
Traitorous Clan Leader Arc
Rai lies in temporary hibernation as the trio train to be stronger. More elders arrive to declare war, amongst whom are traitor ex-noble clan leaders: Zarga and Urokai. Elsewhere, a war of modified humans break out in Ye Ran grounds.
This is the last arc of Season 5 where Rai awakens just on time to save his followers. The reunion with ex-clan leaders do not result in a happy ending as Rai has to execute their punishment as the judge of all nobles. Union finally becomes aware of the existence of the Noblesse and temporary repose from war follows. Another new being is shown asleep in a lab tube...