Kazumasa Oguro, a former Finance Ministry official and now a professor of economics at Hosei University, says he was stunned when he heard that ministry officials had admitted to doctoring 14 public documents on the shady land deal with school operator Moritomo Gakuen, a scandal that has rocked Prime Minister Shinzo Abe's Cabinet.

"A bureau chief alone wouldn't be able to rewrite everything. So several other people had to be involved," said Oguro, who worked at the ministry for about 10 years from 1997. So the still unidentified officials who doctored the papers should have been well aware of the "graveness" of their act, he added.

Falsifying a public document is a crime that is punishable under the law. In addition, the Moritomo documents were kessai bunsho (settlement documents), which need to be formally approved by a number of officials when collective decisions are made at the ministry.