Sanpei Nowaki is a Takanoha High School student who initially sports long hair but shaves his head entirely upon discovering the protagonist’s aversion to long-haired boys. His defining trait is steadfast loyalty, manifesting in constant, earnest pursuit of the protagonist across campus as he reverently dubs her "his goddess." Unaware of her covert mission, he injects humor through relentless devotion, countering hostility with cheeky quips about relishing their confrontational exchanges.

Within the original manga, he serves as comic relief, his exaggerated reverence and obliviousness to the protagonist’s secret operations contrasting her seriousness. The live-action adaptation preserves his schoolmate role, heightening his ignorance of her true identity to offset darker story tones with levity. The OVA mirrors his core persona, prioritizing unwavering allegiance over plot influence, cementing his role as a humorously dedicated follower.

His background remains unexplored across official media, with no elaboration on family, history, or motivations beyond his idolization of the protagonist. No documented narratives link him to criminal activity or expanded arcs beyond his established roles in the manga, TV series, or OVA.