University student Sogawa Ichika inherits 5 trillion yen from her father all of a sudden and attempts are made on her life by his siblings. The avaricious family has struck a deal to let the person who kills Ichika first have all the money to himself or herself and tries all means to take her life. Ichika's housekeeper hires the investigator Chikumagawa Hikaru, who has a perfect record of solving cases before they happen, to protect her.