Shuuichi is the human that carries the soul of a demon named Youko Kurama. Youko Kurama escaped to the Human World after being wounded in the Makai (demon world), and implanted his soul into a human child. Shuuichi has many memories of his days as Youko, but human feelings have caused him to become a kind and gentle person (though, sometimes he can still be ruthless). In this new form, he is less powerful but still posesses the ability to control plants that he uses as weapons.

In his everyday life, he is the popular and intelligent Minamino Shuuichi. He is worshiped by almost every girl in his school for his good looks. He is incredibly intelligent, which makes him the brains of the Rekai Tantei (spirit detectives).