If you’re wondering about “the assassin who returned as the Duke’s son,” this is the premise of the popular fantasy manhwa The Reborn Young Lord is an Assassin. The story follows Cyan Vert, the illegitimate son of a powerful Duke and the empire’s greatest assassin. In his first life he loyally served his family, only to be betrayed and killed by his older brother. As Cyan is about to be fatally struck, he suddenly wakes up as a boy again – meaning the young lord has been reborn. With full memories of his past life, Cyan vows to change his fate and live only for himself, setting the stage for a dramatic tale of revenge and self-discovery.
Story Premise and Plot
In his original life, Cyan Vert was famed across the empire as a top assassin, but he was never treated as a true son of the house – he lived in the shadow of his charismatic half-brother, Duke Aschel Vert. When Aschel betrays him, Cyan is killed. Thanks to a mysterious second chance, he regresses to his childhood and gets to start over. Now determined never to be weak again, Cyan trains intensely in swordsmanship and magic (even mastering a dark, sentient sword) so he won’t be betrayed a second time. This “second chance” angle is central: Cyan remembers every detail from his first life, and he uses that knowledge to write a new destiny for himself.
Along the way Cyan confronts his old enemies and protects those he cares about. For example, he rescues Princess Arin Severus (a fallen imperial princess) who becomes his ally. He also befriends Luna Rainriver, a clever classmate from the royal academy. These relationships – plus Cyan’s adoptive dragon-human ward Nana – add warmth and depth to the story. At its heart, the plot mixes betrayal, revenge, and redemption: Cyan was betrayed by the one person he trusted most, and now he’s bent on preventing the tragedies of his past.
Main Characters
Cyan Vert: The protagonist. Illegitimate youngest son of Duke Wallace Vert and a prodigious assassin. He was considered weak in his family, but in truth he was the empire’s greatest assassin who was killed by his own brother. After regressing, Cyan trains hard to become even stronger.
Aschel Vert: Cyan’s elder half-brother and the previous “Guardian of the Continent.” Charismatic and revered, but secretly jealous of Cyan’s talent. Aschel’s betrayal (killing Cyan) is the trigger for the whole story.
Ellis Vert: Cyan’s older sister. A talented swordswoman and kind person who cared for Cyan. (She dies in the first life, but Cyan remembers her and wants to honor her memory.)
Princess Arin Severus: A former princess who was labeled a traitor in the imperial civil war. After Cyan rescues her, she becomes his fiancée and close ally.
Luna Rainriver: A classmate at the Royal Academy. She has unique magic ability and becomes friends with Cyan. Her intelligence and loyalty make her a valuable companion.
Nana: Although not in Cyan’s first life, in his new life Cyan meets Nana, a young dragon-human girl. Nana becomes his adoptive daughter who affectionately calls him “Papa,” adding a familial bond and emotional stakes.
Each supporting character highlights a different aspect of the story – from Cyan’s conflicted family to the allies he gains. Together they help fill out the rich world of the Ushif Empire and underscore Cyan’s growth from a lonely, betrayed boy into a powerful leader.
Themes and Highlights
The Reborn Young Lord is an Assassin blends action-packed fantasy with emotional drama. Here are some key features that make the series engaging:
Second-Chance Story: A core appeal is the reincarnation/regression angle. Cyan remembers his past life, so readers see how he uses that knowledge to prepare for challenges he once failed. This “do-over” premise creates suspense because you wonder how he’ll change events this time.
Intense Training & Power Growth: Even though Cyan awakens as a child, he was already skilled. Now he trains even harder. He masters shadowy “mist” powers and a powerful sword (Kaeram) to ensure no one can defeat him easily. His battles are thrilling and show how far he’s come.
Family Betrayal and Revenge: The emotional core is Cyan’s relationship with his family. Having been betrayed by the person he trusted most, Cyan’s journey is fueled by his vow of revenge. Themes of betrayal versus loyalty are woven through every encounter.
Fantasy Setting: The Ushif Empire is rich with magic, royal intrigue, and even mythical creatures. Diana brings in magic schools, demon armies, and ancient swords. This world-building draws readers in, mixing familiar fantasy tropes (knights, dukes, academies) with unique twists (e.g., dragon-human characters, mana swords).
Compelling Hero: Unlike many aloof heroes, Cyan has a calm, analytical personality and even a subtle sense of humor. He often surprises others with his strategic thinking. Despite his dark powers, he genuinely cares for his friends. This mix of cool confidence and hidden kindness makes him a memorable lead.
Fans also point out the balance of action and heart. There are epic sword duels and magic battles, but also quiet moments of character bonding. For example, Cyan’s interactions with his sister, his fiancée Arin, and his young ward Nana show different sides of his character.
Publication and Popularity
The Reborn Young Lord is an Assassin started as a Korean web novel by author CoffeeLime. It began serializing online in late 2023 and quickly gained a big following. A comic adaptation (webtoon) launched soon after and updates weekly (currently every Monday). As of early 2026, the series has tens of millions of reads on Webtoon. The official Webtoon page shows over 53.7 million views and 1.1 million subscribers – a clear sign of its popularity.
Reviewers and readers praise the series for its compelling narrative and detailed world-building. Critics note that themes of betrayal, revenge, and redemption “resonate deeply with its audience”. In short, it’s regarded as an exciting and well-crafted fantasy story, making it a must-read for fans of magic-based adventure and clever protagonists.
Key Takeaways: Whether you stumbled on “the assassin who returned as the Duke’s son” by name or by accident, know that it refers to this gripping fantasy saga. It’s a regression fantasy where a skilled assassin becomes a noble’s son again, using his second chance to change everything. With its mix of action, magic, and emotional drama, this manhwa keeps readers hooked from the first chapter.
Title: The Reborn Young Lord is an Assassin (also called The Regressed Son of a Duke is an Assassin).
Main Plot: Cyan Vert, once a legendary assassin, is betrayed and reborn as a boy. Now he seeks revenge and autonomy.
Genre: Fantasy/Regression – features magic, swordplay, and noble politics. Themes include betrayal, revenge, and redemption.
Status: Ongoing; it’s a hit webcomic updated weekly, with over 100 episodes available.
Popularity: Over 53 million views on Webtoon. Readers praise its exciting story and deep characters.
Whether you’re new to the story or just discovering it by this name, The Reborn Young Lord is an Assassin delivers a thrilling fantasy adventure about second chances and overcoming one’s past. It answers the query “The assassin who returned as the duke’s son” by showing exactly that: a mighty assassin regressing into the Duke’s household to rewrite his destiny.
