Tokino Mitani runs a watch shop, located on a street far from the downtown area. She is 20-years-old and inherited the watch shop from her grandfather. Unknown to most, she is also an excellent private detective and offers an alibi cracking service. She can crack someone's false alibi by using logic based on time and a watch. She gets paid 5,000 yen for that service. Yoshiyuki Saji was an elite police officer, but he attempted to uncover corruption within the police department. This caused Yoshiyuki Saji to receive a demotion to a police station in a rural city. He moves alone there, leaving behind his wife and child. He lives at a boarding house, where Tokino Mitani lives. Yoshiyuki Saji does not get along with the other detectives there. He struggles to solve a case, and he hears about Tokino Mitani's ability as an alibi cracker. He doesn't want to ask for her help because of his pride as a police officer, but ends up requesting her help on a case.