Hajime Kindaichi is a high school student known for apparent laziness, poor academic performance, and apathy toward school life. Yet he conceals a genius-level IQ of 180 and extraordinary deductive abilities inherited from his grandfather, the famed detective Kosuke Kindaichi. He deliberately masks his intellect to blend in with peers.

His appearance features distinctive large eyebrows and a ponytail. Personality-wise, he displays lecherous tendencies balanced by a chivalrous core, often luring suspects into complacency by feigning incompetence before trapping them. He demonstrates fierce loyalty, particularly toward his childhood friend and eventual wife, Miyuki Nanase, whom he protects relentlessly.

His investigative methods include catchphrases like "I swear it in the name of my grandfather!" when taking on cases and "All the mysteries are solved!" upon concluding deductions. He utilizes sleight of hand during investigations and engineers traps to expose culprits when evidence is lacking.

Repeated exposure to traumatic murders during his youth leaves a lasting impact. As an adult, he abandons detective work to become a public relations manager at Otowa PR Company. Despite striving for normalcy, he remains a "mystery magnet," unwillingly dragged into cases. His reluctance stems from the emotional burden of witnessing repeated deaths, though he still solves crimes when compelled.

In the "Kyuuketsuki Densetsu Satsujin Jiken" case, he initially scoffs at vampire rumors at a themed inn but must investigate when guests are murdered with neck wounds mimicking vampire bites. His deductive prowess unravels the crimes, systematically debunking supernatural elements through logic.

Long-term development sees him marry Miyuki and father a child, transitioning from adolescent perversions to familial responsibility. He sustains intergenerational bonds, such as with Inspector Isamu Kenmochi, and occasionally partners with rivals like Akechi during critical investigations.