In a bustling office in downtown Kyoto, three colleagues, Ishikawa, Byrne, and Khadijah, find themselves embroiled in a predicament surrounding a misplaced report. Ishikawa, who is known for her organizational skills, had finished compiling a crucial report the previous day, which she placed on her desk before leaving. When she arrives the next morning, the report is missing. She suspects that either Byrne or Khadijah may have taken it, as they both stayed late in the office after she left.

Byrne, who has been known to borrow notes from Ishikawa without asking, didn't see the report on Ishikawa's desk when he left, an hour after her. He assumes that Khadijah, who is often forgetful, may have mistakenly taken the report while gathering her own documents. However, Byrne is unaware that Khadijah left the office right after Ishikawa and did not return, as she had a family emergency that night.

Khadijah, being in a hurry, didn't notice Ishikawa's report and has no knowledge of its existence. When Ishikawa confronts her about the missing report, she is confused and denies seeing it, thinking perhaps Ishikawa misplaced it herself.

Unbeknownst to all three, the cleaning crew came in after hours and, finding the report on Ishikawa's desk with other papers to be shredded, mistakenly disposed of it. The cleaning crew manager doesn't know the significance of the papers but assumes they were correctly placed in the shred bin for disposal, as it is company policy to dispose of all papers in the shred bin.

Now Ishikawa is certain that one of her two colleagues has the report. She needs to understand what Byrne and Khadijah know about the report's whereabouts to figure out what happened to it. The problem becomes one of unraveling who knew what, when, and whether the misplaced report could have been taken by someone unaware of its significance.
To discern what happened to the missing report, Ishikawa has to evaluate the information she obtains from her colleagues, as well as the circumstances surrounding its disappearance. Ishikawa knows she left the report on her desk. She must construct a timeline based on her departure and the exits of Byrne and Khadijah, considering their habits and known information.

Byrne stayed in the office an hour later than Ishikawa and did not see the report on her desk, suggesting the report disappeared within that hour. However, he is mistaken in his assumption that Khadijah took the report because his information about her staying late is incorrect. He could not have known about Khadijah's family emergency, as it was sudden, and she left quickly without speaking to anyone. Moreover, Byrne's past behavior of borrowing Ishikawa's notes without permission could lead Ishikawa to suspect him, but his lack of knowledge of the report's existence undermines this suspicion.

Khadijah, who left immediately after Ishikawa, is not likely to have taken the report as she was focused on her family emergency. Additionally, Khadijah's statement of confusion when confronted, coupled with her characteristic forgetfulness, leads to the assumption that she genuinely does not know about the report. The timing of her departure also provides her with an alibi, as Byrne, who left later, did not see the report on Ishikawa's desk.

The pivotal piece of information comes from the cleaning crew, which Ishikawa may not have considered initially. The fact that no one saw the report after Ishikawa left indicates the possibility of its unintended disposal. If Ishikawa recalls or checks the company policy on disposing of papers and the timing of cleaning crew activities, she could deduce that the report might have been misclassified as shreddable documents and disposed of accordingly.

By considering what each colleague knew and when they were present or absent from the office, Ishikawa could conclude that neither Byrne nor Khadijah took the report deliberately or accidentally. Instead, it is more plausible that a breakdown in procedures occurred with the cleaning crew's misinterpretation of the shred bin policy. This would align with all known facts: Byrne's account of the report's absence from Ishikawa's desk, Khadijah's confusion and swift departure, and the company policy on disposing of documents left in certain areas.