Gu Lin is a two-year-old auspicious beast cub who is attempting to integrate into human society while attending daycare. During a routine outing, he is unexpectedly pulled into a horror livestream game instance titled Mermaid Town. Upon arrival, he finds himself in a thick, deathly fog alongside nine other adult players. Due to his small stature, pale skin, and Ultraman backpack, the other players initially mistake him for a ghost doll NPC. The system announces the mission: obtain pearls formed from mermaid tears or survive for three days. The other players view Gu Lin with a mixture of pity and suspicion, assuming he is a helpless child who will not survive the horrors of the game. Gu Lin, however, is unfazed by the terrifying atmosphere. His primary concerns are hunger and completing the mission so he can return home before his older brother discovers he has been gone too long.
The group is soon surrounded by split-tailed mermaids emerging from the fog. These creatures are grotesque, with white, pupil-less eyes and split fishtails that drag on the ground. One mermaid kills a player by sucking out his brain, causing the fog to dissipate and the creatures to retreat. The town mayor, a chillingly polite but menacing figure, arrives with four NPCs and a pit bull. He reveals that the dead player was accepted as a gift to the town and that the players are there for the upcoming Mermaid Festival. The mayor shows a strange leniency toward Gu Lin, likely due to the cub's innocent demeanor and lack of fear. Gu Lin, oblivious to the danger, asks the mayor if there are any tasty fish, further confusing the NPCs.
The players are led to a public canteen for a meal, where they encounter more mermaids working as citizens, including street sweepers and servers. These mermaids have normal black eyes and are beautiful, contrasting with the monstrous ones in the fog. Gu Lin, driven by hunger, charges into the canteen and uses his cuteness to secure a large amount of food from the staff, who seem enchanted by him. He shares his kindness with Lin Xingchi and Su Qiao, who have taken protective roles toward him. Meanwhile, another player, Scarface, harbors intense malice toward Gu Lin, resenting the cub's popularity with the livestream audience and the points he accumulates. Scarface attempts to sabotage Lin Xingchi and Gu Lin during the meal, trying to delay them as the allotted time expires. The story follows Gu Lin's unique perspective as he navigates this deadly environment, treating the horror elements with childlike curiosity while his companions struggle to survive the psychological and physical threats posed by the mermaids and the hostile NPCs.
