Fermi Amati is a young merchant who appears in the town of Kumerson during the events of Spice and Wolf II. By profession, he is a fish broker or fishmonger and, like the protagonist Kraft Lawrence, he is a member of the Rowen Trading Guild, which is based in the same hometown as Lawrence. In terms of physical appearance, Amati is depicted as an adolescent, likely around fifteen to sixteen years of age. He has short blonde hair, blue eyes, and is considered quite handsome, notably more so than Lawrence, who rarely receives compliments on his looks.

Personality-wise, Amati initially appears as a cheerful, helpful, and ambitious young man. He is confident and successful in his business dealings for his age, having already established himself with a good reputation as a seafood merchant and managing three wagons. However, beneath this pleasant exterior lies a tendency towards impulsiveness and rash action. He operates on a strong, if misguided, sense of chivalry, which leads him to act decisively when he believes someone is being treated unfairly. His primary motivation is a sudden and intense romantic infatuation. Upon meeting Holo, he falls in love with her at first sight, a feeling that overrides his otherwise shrewd business sense. He is led to believe, due to a ruse Holo concocts for her own amusement, that she is a gentle and pious young nun bound by a heavy debt to Lawrence. Consequently, Amati's main goal becomes the liberation of Holo from this perceived servitude, with the intention of proposing to her afterward.

Amati's role in the story is as the primary antagonist for a key narrative arc. His challenge creates a direct conflict between his own desires and the growing bond between Lawrence and Holo. The central conflict emerges when Amati, misunderstanding the intimate and complex nature of Lawrence and Holo's partnership, publicly issues a formal merchant's challenge. He presents a contract declaring that he will pay off Holo's supposed debt of one thousand silver coins, effectively purchasing her freedom and immediately proposing to her. This action forces Lawrence to compete in a high-stakes financial duel in the pyrite market to prevent Amati from earning the necessary funds and thus losing Holo. Amati serves as a catalyst who forces both Lawrence and Holo to confront their own feelings and the strength of their relationship.

Regarding key relationships, Amati's connections are largely defined by his infatuation with Holo and his rivalry with Kraft Lawrence. He becomes a rival to Lawrence, initially friendly but turning hostile when he feels Holo is being mistreated. Their competition culminates in a tense economic battle where Lawrence uses complex credit transactions and futures trading to manipulate the market price of pyrite. His relationship with Holo is entirely one-sided. He sees her as a delicate maiden in need of rescue, completely unaware that she is the ancient Wise Wolf of Yoitsu, who finds his presumptuous and unsolicited proposal deeply insulting. Holo ultimately works behind the scenes to ensure Amati’s failure, selling her own stockpile of pyrite to crash the market and prevent him from winning the challenge.

Amati undergoes a distinct, if brief, character development. He begins as a promising, ambitious, and honorable young merchant with a bright future. He is so confident in his plan to profit from the pyrite speculation and his romantic intentions that he publicly declares his challenge. However, his failure is total and humiliating. The financial losses he suffers, combined with the public nature of his defeat and Holo's ultimate rejection, lead to a complete mental and emotional collapse. He ends the arc frozen in shock and humiliation, having lost both his fortune and his dignity, becoming a cautionary tale and a laughingstock among the other merchants for having reached for another man's woman.

In terms of notable abilities, Amati is a skilled and knowledgeable merchant, particularly in his specialty of fish trading. He demonstrates a keen understanding of market dynamics and is capable of executing ambitious speculative trades, as shown by his plan to amass a fortune by investing heavily in the rising value of pyrite. He is also a capable financier, having accumulated a considerable sum of money for his age. However, his ultimate flaw is that his emotional impulsiveness undermines his otherwise proficient mercantile acumen. His ability to read a situation is blinded by his infatuation, leading him to underestimate both the cunning of Lawrence and the true nature of Holo.