Asked whether Abe's comment in a lower house Budget Committee session on February 17 past year, in which he said, "I will resign as prime minister as well as a legislator if it turns out that either my wife or I was involved (in the land sale)", affected the ministry's decision to alter contents of the documents, Sagawa said, "My answers (in the Diet) did not change before and after (the prime minister's comments in the Diet)".
Hundreds of protestors, including opposition lawmakers, demonstrated in Tokyo on Friday to demand Prime Minister Shinzo Abe resign over a favouritism and cover-up scandal that has battered his popularity.
Sagawa is also under investigation by Osaka prosecutors on suspicion of destroying negotiation records and other documents that would have served as a record of ministry officials selling the plot of state land at just a fraction of its appraisal value.
When asked about the deletion of key words in the documents, including Akie Abe's name, Sagawa declined to answer questions.
The Finance Ministry has conceded that 14 documents related to the cut-price land transaction were altered between late February and April past year after officials at the Financial Bureau ordered its regional bureau in Osaka to do so and insisted Sagawa having played a key role.
Abe has apologized to the public over the document tampering, but repeatedly denied his or his wife's involvement.
Japan protestors demand prime minister Abe resign over scandal
On Monday he pledged a "thorough investigation so that everything can come to light".
The opposition says Sagawa's testimony "is only a first step towards revealing the whole truth" about the scandal.
Sagawa told lawmakers several times in 2017 that sale price had been correctly calculated and that there was no evidence that there had been any political interference. The ruling Liberal Democratic Party (LDP) adopted a proposal to revise the constitution during a convention on Sunday.
The affair took a tragic turn earlier in the month when an official from the finance ministry apparently involved in the scandal took his own life.
An Asahi News Network poll conducted over the weekend showed Abe's approval rating fell 11.7 percentage points to 32.6 percent over the past month, while disapproval rose 13.2 points to 54.9 percent.