Tachibana Giou acts as steward of Twilight Mansion, the central hub for the Giou clan. He supervises the Zweilt guardians, viewing them as his children and calling himself their caretaker or "Herbergvater." A high-ranking clan member, he regularly consults with leader Takashiro on strategy and operations. His personality is upbeat and conversational, often employing humor to sustain dialogue. While typically lighthearted and occasionally childlike, he reveals maturity and strictness when required, especially concerning Zweilt safety or discipline. He mediates conflicts among the guardians, listens to their personal concerns, and serves as the group's emotional anchor. A constant distinctive quirk is his ever-present unconventional hats. He habitually assigns nicknames to others, favoring them over given names, reinforcing his informal and approachable nature. Ambiguous manga remarks suggest he might be an Opast—a type of demonic entity—though the sincerity of these statements remains unclear and could be part of his humor. Tachibana persistently, though unsuccessfully, strives to reconcile the Zweilt with their biological families, particularly Hotsuma Renjou. Intelligence and foresight underlie his playful exterior, as he consistently prioritizes the well-being and unity of the guardians under his care.