The story begins with a brutal battle in a dimly lit cave where two trolls, "Occhan" and "Kado-chan," ambush a party of five adventurers. Despite the adventurers' efforts, the trolls' tough hide and regeneration abilities prove too much. Occhan, a Shape-shifter capable of transforming into a human, uses a spell to disorient the cleric, leading to the adventurers' swift defeat. After the battle, Kado-chan inquires about Occhan's impending departure from their monster role. Occhan reveals his intention to retire, leave the dungeon, and live among humans, even transforming into a human form to demonstrate his ability. He explains that his Shape-shifter nature allows him to mimic any form, including a troll, making him indistinguishable even to other monsters.
Occhan then travels to the city of Sabalcan, a hundred-year-old settlement built atop a dungeon. He heads to the Adventurer's Guild to report a spice-gathering request. He meets Alisa, a kind guild receptionist, and delivers a large quantity of pepper. The price for pepper has significantly increased due to the growing dangers in the jungle, with monsters and dangerous creatures making it hazardous for ordinary people. This situation worries Occhan, as he needs to maintain a low profile as an unremarkable middle-aged adventurer to live among humans. He also attempts to sell Aconite, which Alisa accepts but at a low price. Alisa mentions that trolls have been sighted in the jungle, a fact Occhan knows is related to his own recent activities. He reflects on his poor spending habits, noting that his earnings are quickly depleted by his preference for the guild's inn and good food.
Alisa calls Occhan over to introduce him to Brenda, a young, new adventurer seeking to take on a tiger extermination request. The guild is concerned about Brenda taking on such a dangerous task alone and wants to pair her with a more experienced adventurer. Despite his initial reluctance to work with others, Occhan agrees to hear Brenda out. The request is for forty silver coins to eliminate a tiger near Corinth village. Occhan finds the reward insufficient for the potential danger, especially if there are multiple tigers or cubs. He also worries about the tiger appearing within the village, which would restrict his ability to transform and fight. He tries to refuse the request, claiming to be a novice, but the Guild Master, a formidable old woman, insists he accept, hinting at future benefits. Reluctantly, Occhan agrees, and Brenda readily accepts his partnership.
They travel to Corinth village, a new settlement of eighty people. The village chief expresses concern about the pairing of an older adventurer and a novice. Occhan questions the chief about the tiger sightings, which have occurred three times in the past month. He investigates the area where the tiger was last seen, near the jungle, and discovers unusual human footprints alongside the tiger's tracks, leading away from the jungle. He also learns that no chickens have been harmed, which is odd for a tiger. He suspects the "tiger" might be a monster that can transform, like a Were-tiger, and that the person who went to Sabalcan to sell spices, Abel, might be involved. He decides to investigate further.
Occhan and Brenda spend two days searching the jungle with no success. Occhan plans to test Abel upon his return by using Aconite, which is known to affect Were-creatures. He struggles with the moral implications of exposing Abel if he is a Were-tiger, as he himself is a Shape-shifter. He decides that if Abel is a Were-tiger and leaves the village peacefully, he will let him go, even if it means forfeiting the reward. He informs Brenda of his suspicions and his plan to pay her twenty silver coins from his own pocket if they abandon the mission. Brenda agrees, though she expresses concern about the financial loss.
The next morning, Occhan informs the village chief that they cannot find the tiger and propose to end the search if no further sightings occur. He then searches the jungle for Aconite. He and Brenda investigate Abel's house, finding it sparsely furnished and packed, suggesting Abel was prepared to flee. They find a cat hairball, further solidifying Occhan's suspicion that Abel is a Were-tiger. When Abel returns, Occhan confronts him, revealing his knowledge of Abel's Were-tiger nature. Abel admits to it and agrees to leave the village the next day. Occhan and Brenda monitor Abel's house to ensure he leaves peacefully. The following morning, Abel departs, thanking them for their understanding. Occhan and Brenda then report the mission as a failure to the village chief and return to Sabalcan.
Back in Sabalcan, Occhan delivers more pepper and a large amount of cinnamon bark to Alisa. The cinnamon bark is in high demand, significantly increasing his earnings to two gold coins and twenty silver coins. He learns that the demand for spices is high due to increased danger in the jungle, leading to lower success and survival rates for adventurers. He reflects on his own use of teleportation magic to navigate the jungle safely. Later, Occhan witnesses Alisa dealing with a new client, Morene, a young priestess seeking to hire adventurers to deal with Ghouls in the public cemetery. The offered reward of ten silver coins is too low for the risk involved, especially since the cemetery is not under any church's jurisdiction. Occhan, feeling a sense of responsibility and perhaps a bit of bravado due to his recent earnings, decides to supplement the reward with his own two gold coins to attract more adventurers.
The next day, a group of seven young adventurers, ranging from twelve to fifteen years old, are assembled through a lottery system to accompany Morene. Occhan is dismayed by their inexperience and inadequate equipment. He confronts Alisa about the guild's reckless decision to send children into a dangerous situation. Despite the children's protests and the guild's rules, Occhan decides to join them, not for the reward, but to supervise the operation. He insists they purchase slings and gather stones, as he wants to avoid close-quarters combat with the Ghouls due to their potential poison.
The group, led by Morene, enters the foggy public cemetery. They encounter six Ghouls. The children's initial attempts to attack with stones are largely ineffective. Morene uses "Turn Undead" to destroy three Ghouls, but the remaining three advance. Occhan intervenes with a "Magic Arrow" spell, revealing his hidden magical prowess. He downplays his abilities, claiming to be a novice mage. After defeating the remaining Ghouls, they discover a place with a strong, unpleasant aura. Following Morene's guidance, they proceed and encounter a Phantom Knight. Occhan, recognizing the creature's intelligence, decides to negotiate. He sends the children and Morene away, feigning a fight to create an opportunity to speak with the Phantom Knight, Servain Carrowell.
Occhan learns that Carrowell seeks revenge on an adventurer named Cain, who betrayed him and caused him to fall into a pit. Occhan agrees to help find Cain in exchange for Carrowell investigating the source of the Ghouls. Carrowell agrees, and Occhan returns to the adventurers' inn. He informs the children and Morene that he has found a lead and asks them to investigate Cain and Carrowell's past. He instructs them to gather information discreetly, not from other adventurers, but from their friends and neighbors, to avoid raising suspicion. He also reveals that Carrowell is missing and that Cain likely died in the jungle while gathering spices.
The children, surprisingly effective, discover that Carrowell was betrayed by Cain, who pushed him into a pit while trying to save him from a poisoned arrow. They also learn that Cain is presumed dead in the jungle. Occhan, impressed by their findings, enters the jungle alone to find Cain's silver key, a keepsake. He finds the key in a remote location, confirming Cain's demise. He then meets Carrowell at the cemetery and presents the key. Carrowell, initially suspicious, accepts the key and, after Occhan's explanation of Cain's betrayal, agrees to investigate the source of the Ghouls. Carrowell then single-handedly defeats the Ghouls near a disturbed grave and retrieves a cursed golden necklace, which he believes is the cause of the Ghouls' appearance. Occhan attempts to remove the curse but realizes it's a temporary fix, requiring a more powerful spell he cannot cast. He agrees to transport the necklace to a church in Sabalcan.
