Janeiro personifies January and embodies winter itself. As leader of the Twelve Months spirits, he presides over their mystical bonfire deep within a snowy forest. He appears as an elderly figure with a long beard, wielding a staff that signifies his authority over the season, his demeanor stern and commanding.

When Anya arrives, forced to seek spring flowers in winter, Janeiro compassionately presides over the group's decision to help her. Under his supervision and authority, he approves the temporary suspension of natural laws, allowing April to manifest spring briefly so Anya can gather Galanthus flowers. Afterward, Janeiro personally presents Anya with a ring, imposing the condition that she must never reveal the existence or location of the Twelve Months. Later, when Anya's stepfamily and the queen discover the gathering, Janeiro and the other months intervene again to protect her.

His powers include commanding winter elements, specifically summoning and controlling blizzards. As January's representative, he holds significant influence within the monthly spirits, his decisions carrying weight in matters of seasonal transitions.