On the third day the clan's special egg hatches — but instead of a powerful ninth‑rank member, a man who just transmigrated wakes up transformed into a small koi in the lake. Seven mermaid daughters inspect him, mock his lack of rank, and argue about eating him for spiritual power. He begs for mercy, claiming to be a lucky mascot. Linda insists he could bring good fortune and urges sparing him, while others dismiss luck in favor of strength. As the sisters bicker, the Devouring Evolution System activates, abruptly raising the stakes and leaving his fate undecided.
The Devouring Evolution System activates and binds to a Lucky Koi at a sealed lake. The system orders: devour other beings to evolve. Fish line up for spiritual meat, but weaker ranks are denied and told the Lake Demon King will eat low-ranked fish at the Hundred-Demon Banquet in three days. Linda gives the protagonist Moonlight Waterweed; frightened but determined, the koi uses the system to devour it. The fish is promoted to the lower tier of the ninth rank and gains a 50% Luck Value. With the deadly banquet looming, survival hinges on whether this upgrade is enough.
Fresh from devouring Moonlight Waterweed, a Lucky Koi levels up to the lower ninth rank and 50% Luck. He tests his new strength, uses the System to scan, and detects faint demonic power about 200 meters ahead. Approaching two creatures locked in combat, he plans to exploit their fatigue and strike before one can eat the Rotten Shark and recover. A taunting fish provokes him and then carelessly rams itself to death. Before the Koi can act, a third predator appears and declares, "Time for a feast!", foiling his chance and leaving danger looming.
After using Luck Value and strategy to kill the Titan Shark, you devour it and trigger a bloodline evolution. Notifications confirm rank promotions, a Luck Value boost, and new skills—Fast Swimming, Sacred Armor, and the racial Nine-Scale Blade—raising you to mid eighth rank. Thrilled by sudden speed and power, you taunt Lady Lily and prepare to fight. Suddenly a voice cries, "Help! You despicable Demon Hunters!" Someone struggles nearby. You decide to investigate, abandoning the immediate duel and plunging toward an uncertain rescue that will test your new abilities.
Fishermen drag three mermaids from a lake, boasting they’ll harvest their skin, flesh and blood for profit. When a so-called demon appears, the hunters mock it and ready a Demon-Killing Crossbow. The creature activates Fast Swimming and Luck Value, breaks the ambush and drives off the attackers, rescuing the mermaids. One survivor, Cindy of the Nine-Apex Clan, calls the rescuer 'Master' and thanks him. She then accuses him of having once called her useless and tried to eat her, leaving the rescuer stunned and their past unresolved.
At Grain Marsh Lake, stunned onlookers—Lily and others—watch the so-called Lucky Koi suddenly transform. System notifications announce a bloodline evolution: he gains the Hidden Dragon's Claw, becomes a Fighting Lesser Dragon, unlocks two skills, and raises Luck to 70%. After completing a disguise, he heads to the Hundred-Demon Banquet and seizes control, addressing all demons: 'Those who obey shall prosper; those who disobey shall perish.' He orders everyone to take their seats and declares the banquet begun. As demons settle, he coldly adds, 'Let's see who will be eaten.'
At the Hundred-Demon Banquet, Jason returns to jeers as other attendees call him a "useless fish" and claim the one who saved them couldn't be him. Jason brags he's reached the seventh rank, but rivals dismiss its value and predict he'll be the first to die. The banquet's first trial, Bear the Queen's Might, is announced. Linda steps forward to shield the group and people hide behind her; someone whispers "Thanks, Linda." The trial begins and proves terrifying, leaving Jason facing public doubt and his survival hanging unresolved.
After they survive, clans receive territory: Ancient Mermaid Clan gets Class B while the Nine-Apex Mermaid Clan is saddled with barren Class D. Jason and Linda prepare to move when rival Jim taunts them, offering to take the women to his palace and send the male to the mines. Linda cites the Queen's grant, but Jim invokes the Hundred-Lake Law from three thousand years ago and emphasizes rank differences—Linda mid-tier fifth, his clan third, Lucky Koi unrated. He claims he can lawfully seize them as servants, leaving their fate unresolved.
At court, Jim of the Ancient Mermaid Clan secures Her Majesty's permission under the Hundred-Lake Law to claim the mermaids as his property. He grabs Linda, provoking the girls to declare a fight to the death while some urge Jason to run. Jason refuses to flee, invokes a System command to remove his disguise, and reveals he has evolved into a lesser dragon. The clan is stunned—none managed such evolution in a thousand years. The episode ends with the discovery that another lesser dragon lurks in Grain Marsh Lake, immediately complicating the aftermath.
Jason, a tired office hand in the modern world, awakens transmigrated as a Lucky Koi and faces cold contempt from the mermaid clan. Rescued by Linda and bound to a mysterious system, he clings to a fragile hope: the system and his rising Luck Value push him through painful evolutions and brutal trials. He defeats enemies, wins the Lesser Dragon Queen’s favor, then uncovers her secret, sinister designs. Betrayed by the very throne that praised him, Jason makes a desperate choice—unite the clan mermaids and lead a revolt. The battle tests loyalty, courage, and identity. In the fire of conflict he sheds his former self and ascends, claiming his place as the True Dragon.