Local media, an employee of the Japanese Ministry of Finance with colleagues, lost the documents containing personal data of 187 people suspected of drug smuggling.
The employee who was reportedly not named, drank nine glasses of beer during a five -hour night exit with employees in Yokakham on 6 February.
Local media said he did not realize that he had lost his bag until he left the train home to another city, Sumida.
The Ministry of Finance stated that it was “deeply sorry” for the incident that “significantly undermined the trust of society”, reports Public Broadcaster NHK.
The bag contained documents that had names and addresses of 187 suspected drugs and marijuana seed recipients, the ministry said.
It also contained business -naut books with the employee’s personal data.
An employee who is appointed to the Customs and Tariff Bureau was not named in the NHK report.
The BBC appealed to the Ministry of Finance to comment on Tuesday, a state holiday in Japan.
Alcohol has long been regarded as social grease for thousands of years in Japan, where business transactions and difficult problems are discussed in beer and saake bottles.
It is believed that alcohol consumption creates a more calm environment for such discussions.