Hokuto Aoi is a 17-year-old male standing 178 cm tall and weighing 59 kg. He fled Japan following its takeover by the unidentified threat Archon, finding refuge and purpose within the specialized defense unit known as the Goulart Knights, dedicated to combating Archon. Typically reserved and taciturn, his rare speech is sharp and critical, often delivering harsh remarks that clash with his composed exterior and undermine the impact of his described beautiful face.

Based at the training institution Goulart Academy, he leads a solitary existence within the Knights, showing no apparent concern for his isolation. His combat role involves directly confronting Archon using supernatural abilities to generate manifestations called "Holy Grail" from his spiritual energy.

A significant duty involves an enforced caretaker role for fellow unit member and classmate, Nil Almars. Hokuto visibly expresses irritation and reluctance towards this obligation, viewing it as an imposition, yet he fulfills the responsibility despite his objections.