Indonesian President Joko Widodo will arrive in Tokyo late on Sunday, kicking off a week-long tour of Japan and China aimed at attracting investment and boosting defence co-operation.
"We want to develop (infrastructure) with particular focus on electric power plants, railways and express ways. I would like to ask Prime Minister Shinzo Abe for co-operation on this issue," Widodo said in footage aired by Japan's public broadcaster NHK.
Widodo, who took office in October, will be in Japan until Wednesday and will meet Abe as well as Japanese businessmen.
Widodo told the Yomiuri Shimbun that he and Abe would sign a memorandum on boosting defence co-operation.
He said that China's claim to virtually all of the South China Sea "has no legal foundation supported by international law".
"We would absolutely like to learn Japan's excellent experiences in protecting its waters," he told the Yomiuri.
China has had occasionally tense confrontations with Japan and Southeast Asian countries -- the Philippines and Vietnam in particular -- over maritime disputes in the East China Sea and the South China Sea, respectively.
Indonesia "is ready to play a role of mediator", Widodo told NHK.
Widodo has vowed to boost Indonesia's economic growth, which slipped to its slowest pace in five years in 2014, and is seeking new investment.
The president, nicknamed Jokowi, will also meet Emperor Akihito during the trip, which is his first as leader outside Southeast Asia.
Widodo, in China from March 26 to 27, will meet President Xi Jinping and Chinese businessmen. He will also participate in the Boao Forum for Asia -- an annual gathering of political and economic leaders.