Hakuro Teshima is working at his veterinary clinic as usual when a mysterious beauty named Kaede Yagami appears. She claims to be his brother's wife and tells Hakuro that his brother Akito Yagami is missing. Kaede suspects a member of the Yagami family is responsible for Akito's disappearance. Hakuro's mother married into the Yagami family after his father died, and Hakuro has been estranged from them since her death. Akito, however, is the rightful heir to a three-billion-yen inheritance, and with the head of the Yagami family on their deathbed, Kaede believes a relative may have kidnapped Akito to get their hands on the money. Hakuro promised himself he would stay away from the Yagami family, but he cannot resist helping a woman in need and goes with Kaede to the Yagami mansion.

Hakuro and Kaede are waiting to meet Makio Yagami, but find him collapsed at the bottom of an escalator. While the paramedics apply first aid, Hakuro and Kaede rush to the Yagami home. Kaede thinks someone from the Yagami family pushed Makio to stop him from leaking information regarding the inheritance. That means anyone who was away from the mansion at the time is a potential suspect. Having only just returned, the family butler also becomes a suspect. However, Kaede is suspected too, since Makio's phone shows that she called him just before his fall. Hakuro defends Kaede but wonders how can she calmly continue her pursual of the culprit without being shaken by Makio's fall. That's when Yuma asks Hakuro to steal Kaede's smartphone, in order to check whether she is Akito's wife.

Motomi tells Hakuro that Kaede was taken away in an ambulance, and he rushes to the hospital. However, Kaede had already returned home, so Hakuro goes to see her where she lives at Akito's apartment. Though she never saw their face, Kaede says someone with a pleasant smell pushed her down the stairs. Kaede visits the Yagami home the following day and hears that the head of the family, Yasuharu, is not doing well. She feigns sympathy with Namie and Shoko and hugs them in order to see what they smell like, but she soon realizes that Yasuharu's nurse, Anri, smells the same as the culprit who pushed her. Kaede also suspects Shoko's daughter Yurika. Kaede tells this to Hakuro, who makes arrangements to meet with Yurika. Meanwhile, Yuma is waiting for Kaede at her home.

Yurika tells Hakuro that her mother, Shoko, left a farewell letter and disappeared, just like what happened with Akito. Yurika asks Hakuro to help search for her, but he does not feel inclined to help since Shoko once bullied his mother. After Hakuro refuses, Yurika tells him not to mention anything to Kaede. Meanwhile, Kaede is at the Yagami home helping care for the bedridden Yasuharu. Namie discusses inheritance with Yasuharu, but he indicates on a character board to wait for Akito before falling back to sleep. Hakuro finishes work and decides to visit Yurika. Yurika shows him around the house to look for clues, and Hakuro finds a suspicious letter from an unknown sender. The letter contains a shocking message. Then, somebody approaches Hakuro from behind.

Hakuro is shocked to learn a member of the Yagami family murdered his mother. Kaede also tells him that Akito was trying to uncover the truth behind their mother's death. Hakuro wonders why Akito never went to him for help. Are his mother's death and Akito's disappearance connected? Makio's mention of something worth more than an inheritance of three billion yen plays on Hakuro's mind, but Makio is nowhere to be found since he disappeared from the hospital. Hakuro takes his mother's belongings to the Kaneiwa home to look things over with his aunt Junko and uncle Kenzo. Junko notices their family album is missing and wonders if the Yagami family threw it out after her death. Junko advises Hakuro to look into their vacant family home in Koizumi. Meanwhile, Kaede and Yuma are meeting alone.