Japan should send a clear message of soul-searching over the war it waged with Asia when it reviews the Constitution's war-renouncing Article 9, said Yukio Hatoyama, deputy secretary general of the Democratic Party of Japan, on Friday.

Hatoyama, who is running for party president in the election slated for late September, caused a stir when he said the article should be reviewed, drawing the ire of former Socialist legislators within the No. 1 opposition party.

At a meeting with reporters on Friday, Hatoyama repeated his willingness to discuss constitutional revision, but stressed that sending the proper message to Asian countries is equally essential.

"I don't think (Japan) has fully communicated an overall view of the past wars," Hatoyama said, adding that Japan, China, South Korea and other countries should try to agree on history.

Hatoyama also argued that it is necessary to conduct constitutional revision from a liberal viewpoint, rather than just a conservative one, and that a lack of balanced debate on the Constitution would lead to a twisted interpretation of the article.

"I want to challenge the taboo (that has hindered discussion on revising the Constitution)," Hatoyama said.