Hikaru Chikumagawa is a private investigator. He has a fussy temperament and he is not good at communicating with others, but he is the fastest detective in the world. Ichika Sogawa is a normal university student. After her father's sudden death, she receives an inheritance of five trillion yen. She is also targeted by her relatives. Private Investigator Hikaru Chikumagawa tries to protect Ichika from harm.