Peter is a young boy who attends the elementary division of St. Tsarl Academy, where he is in the fifth year. He is connected to the Devil Store, the rival convenience store in the Bikkuri-no area, and is a regular at its Bikkuri-no branch. He has short blue hair and blue-green eyes, and he carries the factor of Peter Miko, an inherited power tied to the Bikkuri-Man seal system that plays a central role in the story.

Unlike the devoted collectors who surround the seal trade, Peter has no genuine interest in Bikkuri-Man stickers. He targets seals on behalf of Maris, the area manager of the Devil Store who operates from the Bikkuri-no branch and quietly gathers rare seals for reasons connected to the larger conflict. Peter's motivation is therefore personal rather than hobby-driven: he pursues seals because Maris asks him to, and his loyalty to Maris defines his place in the story. He belongs to the group of characters aligned with the Devil Store, alongside figures such as the young mafia heir Hood, who uses the store to recover rare seals and shares a relationship of mutual convenience with Maris.

Within the larger plot, Peter is drawn into the schemes of the Devil faction. The story indicates that both he and Maris are coaxed and manipulated by Super Devil, the former leader of the demon forces, who uses them as part of his plan to revive in the modern era. Peter's development is limited and closely tied to that manipulation, keeping him a supporting presence in the seal battles. His notable ability lies in the Peter Miko factor, which connects him to the series' transformation system; like other factor-holders, he is linked to the visual change and divine union powers that allow characters to merge with the strength of a matching seal.