Yanagibashi Bridge

Yanagibashi Bridge is the January entry in a twelve-month list of bridges in the Nihonbashi area, a pattern that links an obscure written clue to an investigation involving Hiromi Asai, Michiko Oshitani, and Shunichi Watabe. The bridge itself is not explained as the site of a decisive crime; its significance lies in how its name recurs on a calendar, in a note among Kyoichiro Kaga’s mother’s effects, and in the detectives’ questions to Hiromi. The list ultimately helps Kaga connect Watabe to Hiromi’s family history and reassess what had happened to her father.

Place and the January Clue

The investigation establishes that the twelve annotated locations are bridges in the Nihonbashi area. Yanagibashi Bridge occupies the first position: January. The other months likewise name bridges, among them Asakusabashi Bridge in February, Tokiwabashi Bridge in April, and Nihonbashi Bridge in July. The complete sequence makes the January annotation part of a deliberate annual pattern rather than an isolated place-name.

The calendar’s notes appear on every page. Investigators find the same month-and-bridge sequence written on a separate sheet, and the two lists match. That correspondence gives the list evidentiary weight, but not an immediate explanation: a search team considers whether the bridges hosted events attended by Mutsuo Koshikawa, yet finds no supporting information. The names remain a puzzle until the investigation broadens beyond the calendar’s possible connection to Koshikawa.

The List as a Route and a Question

Kyoichiro Kaga’s mother’s effects include a note listing the bridges beside the months. Kaga tells his colleagues that its handwriting is not his mother’s, and that its ownership is uncertain. He has already compared it with Koshikawa’s calendar: the places and dates are a perfect match. Because Kaga suspects the note may have been written by Watabe, a man he knows little about, he asks the task force to arrange handwriting analysis.

The detectives also test what the months might signify. As they travel by boat through the waterways, Shuhei Matsumiya reads out the list and wonders whether each month corresponds to when a bridge opened. Kaga checks construction dates for the first entries: Yanagibashi Bridge was completed in July 1929, while Asakusabashi Bridge was completed in June 1929 and Saemonbashi Bridge in May 1930. The dates do not match the list’s January, February, and March order, eliminating one straightforward interpretation without resolving the clue.

Hiromi and the January Visit

The January entry becomes pointed when Kaga tells Hiromi Kadokura that he understands she visited Yanagibashi Bridge that month. Hiromi frowns and asks what he means, then appears surprised by the specific claim. Kaga opens his notebook and questions her response. The exchange turns a general list into a question about her movements: Yanagibashi Bridge is no longer only one name among twelve but a possible connection between the sequence and Hiromi.

Hiromi recognizes the list from an earlier interview with Sakagami, who had shown her a sketch and asked what the annotations meant. By the time Kaga brings it up, she understands that he is investigating Michiko Oshitani’s murder. Kaga says he is following a particular angle because the bridges all lie within his precinct, and asks what she thinks the list means. The bridge names thus become part of a direct investigative encounter, while Hiromi’s recognition of the case makes clear that the questions are not casual local-history research.

From Bridge Names to Family History

The clue’s importance expands when Kaga sets the list against the relationship between Hiromi Asai and Watabe. The investigation had concentrated on Seizo Naemura, a man thought to connect Hiromi and Michiko, but Yasuyo Miyamoto’s testimony shows that Naemura is not the missing person they seek. Reconsidering the evidence, Kaga notes that Hiromi and Watabe had been connected for at least ten years, that Watabe had few other relationships, and that Hiromi may have supported him financially. Given Watabe’s estimated age, his disappearance, and his acquaintance with Michiko, Kaga concludes that he fits the pattern of someone exceptionally close to Hiromi: her father, Tadao Asai.

The hypothesis also reopens the account of Tadao’s supposed suicide. The reported death is recorded in the files of Biwa Gakuen Orphanage but lacks official documentation, and Hiromi’s former classmates do not remember her father’s suicide. Kaga reasons that the death may have occurred elsewhere and that the dead man may not have been Tadao at all; Tadao could have used another person’s death to erase his own identity. In this chain of reasoning, the bridge list is one component of a wider inquiry, not proof by itself. Its repeated correspondence with the calendar and its suspected connection to Watabe help redirect attention from a presumed stranger to the concealed history of Hiromi’s family.

Yanagibashi Bridge’s narrative role is therefore chiefly evidentiary and structural. The January annotation gives investigators a concrete location to ask about, while the full twelve-bridge sequence ties separate traces together: Koshikawa’s calendar, the unexplained note in Kaga’s mother’s apartment, Hiromi’s movements, and Watabe’s long-standing connection to her. What begins as a question about a bridge becomes a route into an identity that had been hidden, and into the family history behind the murder investigation.