Hikaru Ichibanboshi is a second-year student at Kanenone Gakuen, an all-boys boarding school in the Japanese countryside. He belongs to the "Baka Trio" with Tadatomo Ijuuin and Taizo Tenjin, united by their relentless pursuit of female attention and frequent comedic mishaps. His name meaning "number one shining star" mirrors his self-image as a charismatic ladies' man.

He meticulously deploys pick-up lines from a book by "Dr. Tanaka" to woo female classmates, though these attempts consistently backfire, leading to public embarrassment. Despite this, he remains the least perverse member of his trio. His primary romantic focus is Futaba Kutsuki, a fiercely independent girl who flatly rejects his overtures.

During Kanenone Gakuen's co-ed trial period, he joins the trio's schemes to interact with female students. These often involve intrusive tactics like distributing overly personal questionnaires, typically provoking Futaba's violent retaliation. His character lacks substantial development or backstory exploration across the television series, original visual novel, or PlayStation 2 adaptations "Green Green: Kane no Oto Romantic" and "Green Green: Kane no Oto Dynamic."

In the OVA "Green Green Thirteen: Erolutions," set months after the co-ed trial, he appears alongside the Baka Trio during events centered on Yuusuke Takasaki and Futaba Kutsuki's reunion. His role remains secondary and comedic, consistent with prior portrayals. Official media, including this OVA, provides no additional history, family background, or substantive evolution for the character.