After losing her mother in an accident when she was a child, aya grew determined to become a detective. She has been on the NYPD's 17th Precinct force for 6 months. Although quiet on the surface, she can be very stubborn and unyielding. She and her partner, Daniel, called"the father and daughter team," occasionally get into arguments because of her stubborn nature.

A veteran detective of the NYPD's 17th Precinct. Although he has 20 years of experience behind him, he believes "a detective belongs in the field" and is not on the road to a promotion anytime soon. He and his wife, Lorraine, got a divorce a year agom so Daniel raises their 8-year old son, Ben, by himself. He is Aya's senior as well as partner and father figure.

An opera singer on the rise. Her long awaited wish to play the leading role comes true in an opera to be held on Christmas Eve. altough she is an introvert and was constantly sick as a child, she began aspire to become and actress after learning about the opera. She occasionally commutes to hospital even now is always carrying some sort of medication.

A scientish who resides in the pharmaceutical department at a Japanese University. After an incident that took place a number of years agom ge gas devoted his studies to mitochondria. Although a very competent scientist, he is completely indifferent to everything else. His clothes are untidy, and his hair is a perpetually uncombed. Naturally, he has no luck with women.