Dennis appears as a secondary character in the narrative and is identified as a friend of Antonio. Both share a perspective that finds humor in Lubicchi's earnest belief in stars beyond the perpetual smoke enveloping their town. The character's full name is given as Dennis Letter the 15th in the English-language version, suggesting a potential ancestral connection to the Letter lineage. This lineage holds historical significance in the town's founding backstory, specifically referencing Silvio Letter, an economist who introduced a unique decaying currency system centuries earlier, and his son, who was involved in establishing the isolated settlement that became Chimney Town. Dennis does not appear in the stage musical adaptation *Poupelle of Chimney Town: The Musical*, where he is listed among the roles omitted from that version.