Kusanagi and Kishitani are in Yukawa's laboratory. Yukawa's surmises the purpose of their visit, which is to ask about the Togashi murder case. He is able to accurately infer this based on the fact that Kusanagi received an urgent phone call in Yukawa's lab on the very same night that news of the murder was reported on the nightly news.

Kusanagi expresses his doubts about the reliability of Yusako's alibi. He emphasizes the difficulty of proving an alibi at a movie theater, which is where Yusako allegedly went around 7 p.m. at nigh on the night of March 10. Kishitani is skeptical that Yusako could've murdered Togashi at that hour, blurting out how an autopsy of the victim's body revealed the time of death to be after 6 p.m. on March 10.

When Yukawa asks if Yusako was able to produce ticket stubs to prove that she had gone to the movies, Kusanagi explains how the ticket stubs had been placed in a theater pamphlet. Yukawa is impressed by this detail, believing it to be a sign of clever planning on the part of the murderer, since placing the ticket stubs in a drawer would make it appear too obvious that the ticket stubs were being used solely for the purpose of establishing an alibi. Having the ticket stubs in a theater pamphlet would seem less suspicious, since people would not be reasonably expected to save their ticket stubs. Yukawa goes so far as to assert that the murderer is "formidable" and should be taken seriously.

As he and Kishitani are about to depart, Kusanagi recalls seeing the return address for Imperial University on Ishigami's mail, which he had noticed while questioning Ishigami. He makes mention of this fact, correctly surmising that Ishigami must have been one of Yukawa's classmates while he was in college, probably an upperclassman. Yukawa confirms that Ishigami was indeed a classmate in the same year as him and produces a yearbook in which a picture can be seen of a younger Ishigami.

While Ishigami was in college, he studied in the math department while Yukawa studied in the physics department. Students had respectfully nicknamed Ishigami "the Buddha" due to his ability to concentrate whole-heartedly on math problems, making use of only a paper and pencil, which often made it necessary for students to approach him from the back and unable to see his face. Yukawa further adds that Ishigami was bona fide genius, the type of student who rarely appeared among students, and expresses surprise over the fact that Ishigami is now a high school math teacher as opposed to a researcher at a private university.

Kusanagi expresses frustration over his inability to read Ishigami's facial expression and detect anything unusual. "No one can know the mind of the Buddha," Yukawa reflects facetiously, later adding that "he's not inerested in anything but math." Before leaving, Kusanagi gives Yukawa the address to Ishigami's apartment.

While in his apartment, Ishigami reflects upon the case, noting how everything was developing as he had expected, with the policy suspecting Yasuko and looking into her alibi on March 10. On the way out of the building, he runs into Yasuko, merely saying a casual greeting in order to avoid giving the impression that they were on intimate terms. Using his usual payphone, he calls Yasuko, who informs him that the detective had gone to the lunchbox shop asking if Togashi had come to the shop. They had also asked if Yasuko's had kept in touch with old colleagues at her former club. In addition, they talked to Misato as she was returning home from school. None of this was unexpected from Ishigami's point of view, and both Yasuko and Misato are able to handle police questioning with poise and discipline.

On his way back to his apartment, Ishigami notices a stranger standing in front of his apartment, whom he recognizes as Manabu Yukawa, his former classmate.