The Nihonbashi district is more than a Tokyo setting in the investigation: it is a place bound to Hiromi Asai’s theatrical beginnings and a carefully chosen route through which she could meet her father, Tadao, in secret. Its bridges provided changing rendezvous points, while its Meijiza Theater connected the hidden family relationship to the night Michiko Oshitani may have seen Tadao.

Setting and Personal Significance

Nihonbashi mattered to Hiromi because the Meijiza Theater was where she first performed. Kyoichiro Kaga later treats that connection as a key to understanding why she and Tadao chose the district for their meetings: it carried a shared significance for father and daughter, not simply a convenient place in Tokyo.

The district’s bridges also offered a practical answer to the problem of meeting discreetly. Rather than choose a fixed point along a riverbank, Hiromi and Tadao settled on bridges as recognizable meeting places. To lessen the chance that their routine would attract attention, they could change the bridge from month to month.

A Calendar of Secret Meetings

The arrangement used twelve bridges in the Nihonbashi district, one assigned to each month. Hiromi bought two cell phones and mailed one to Tadao. At their next meeting, in August, they spoke from opposite ends of Edobashi Bridge. The monthly bridge list gave their contact a structure that was both intimate and cautious: a shared schedule organized around public places where they could communicate without standing together.

Kaga found a handwritten list in his mother’s apartment matching the bridge-and-month pattern on Mutsuo Koshikawa’s calendar. He did not know who had written the note or what it meant, but he told his superiors that his mother had had a long-term relationship with Shunichi Watabe and suspected Watabe had written it. The list’s connection to the Nihonbashi bridges later became part of the chain of clues linking Watabe to Hiromi and her family.

The District in Kaga’s Reconstruction

Kaga reasoned that Hiromi and Tadao had tried to minimize contact, even though Watabe had traveled to Tokyo, particularly to Nihonbashi. He proposed that the bridge schedule let father and daughter meet without being seen together, while acknowledging that he could not establish whether they met every month. The district thus became a means of concealing their relationship and, years later, a pattern from which the investigation could infer it.

The Meijiza supplied a second connection. Hiromi’s play had opened there on March 10 and run for fifty days, an unusually long engagement for the theater. Kaga believed Tadao might have attended the opening night to see his daughter’s success at the theater where she had first performed, despite the risk of being recognized. This remained his reconstruction, not a confirmed account of Tadao’s attendance.

Kaga also theorized that Oshitani had gone to the opening. She had spent the preceding night at a business hotel in Kayabacho rather than return to Shiga, and same-day tickets had been available. Kaga inferred that she bought one and, at some point before the performance, during the interval, or afterward, recognized Tadao. Because she had been Hiromi’s close friend, Kaga considered it plausible that she would remember what Hiromi’s father looked like. The district’s theater and bridges therefore brought two kinds of evidence together: the private pattern of father-daughter contact and the possible public encounter that could have exposed Tadao’s assumed disappearance.