Hajime do Mon is the owner of the Café Vantaleimo. He serves as the foster parent for the main protagonist, Sōgo, having taken care of the orphaned boy since he was a child.

Before becoming a café owner, Hajime had a different life as a researcher of crystals and was a highly capable soldier whose military achievements were known throughout the land of Indigo. He is presented as a kind and responsible individual, a man deeply committed to protecting those close to him. Despite his calm demeanor as a café proprietor, his past skills as a fighter remain sharp and continue to surface when needed. His appearance is that of an adult male with brown hair and brown eyes, and he is typically depicted wearing glasses, suspenders, and a neckerchief.

Hajime’s primary role in the story is as a guardian to Sōgo, providing him with a home and a familial bond. His motivation is rooted in this responsibility and a genuine care for his foster child’s well-being. The most significant relationship in his life is with Sōgo, whom he raised. A notable event in his character development involves his ultimate sacrifice; he meets his end by the sword of a character named Lillian, who was disguised as Sōgo’s mother. In this final act, he demonstrates his unwavering resolve and willingness to do anything for his loved ones. His abilities are not extensively showcased, but his background indicates he is a formidable combatant with past experience as a soldier and researcher.