Ubertino is a client and employer of Leo, the owner of the painter's workshop where Arte works. He acts as Leo’s boss and stands as his most troublesome client, frequently making unreasonable demands that spark arguments between them. Despite these conflicts, Leo consistently accepts and fulfills Ubertino's requests. The two share similar personality traits. Ubertino first encountered Leo when he was a new apprentice in Ezio’s workshop. After Ezio fell ill and passed away, Ubertino honored his late teacher’s request by taking care of Leo, instructing him in basic financial matters so he could live independently. It was Ubertino who eventually purchased the workshop for Leo when he became an independent painter. He takes an interest in Arte, often asking about her development as a painter. While Arte finds him somewhat intimidating and occasionally compares him to Leo, she also admires his philosophy. In later chapters, Ubertino falls ill and passes away. Before his death, he voices regret at not being able to see Arte one final time.