Here's your 10-point cheat-sheet to what's on the PM's agenda.
PM Modi, 63, will first meet host Prime Minister Shinzo Abe privately in the historic city of Kyoto before holding official talks in Tokyo, seeking to boost trade between Asia's second and third largest economies.
Both premiers are right-wing nationalists elected on a pledge to revive their countries' economies, and lead countries embroiled in territorial disputes with China. The United States, Japan's key ally, is concerned about Beijing's growing economic and military clout, and would welcome a closer relationship between New Delhi and Tokyo, which geographically bookend China. (Narendra Modi and Shinzo Abe: A Rare Affinity)
In a statement released yesterday, PM Modi said he is keenly looking forward to the visit. Calling Japan one of India's "closest partners in political, economic, security and cultural realms," he added that he is confident that his visit will "write a new chapter in the annals of the relations between Asia's two oldest democracies and take our strategic and global partnership to the next higher level." (PM Modi's Full Statement on his Visit to Japan)
Mr Modi is traveling with a large delegation studded with some of India's biggest industrialists including Reliance's Mukesh Ambani and software giant Wipro's Azim Premji. The PM will seek Japanese support in infrastructural developments.
This could include Japanese investment for the high-speed 'bullet' trains that the PM has promised. His government has said the country's dilapidated railways needed an "immediate course correction". (To Tokyo With Love: PM Narendra Modi Tweets in Japanese Ahead of Key Visit)
India is hoping to win Japanese backing for a nuclear energy pact and lure investment into its $85 billion market while addressing Japan's concern about nuclear proliferation.
India has been pushing for an agreement with Japan on the lines of a 2008 deal with the United States under which Delhi was allowed to import U.S. nuclear fuel and technology without giving up its military nuclear programme.
But Japan wants explicit guarantees from India, which has not signed the international Nuclear Nonproliferation Treaty, to strictly limit nuclear tests and to allow more intrusive inspections of its nuclear facilities to ensure that spent fuel is not diverted to make bombs. An agreement is not expected to be sealed at the bilateral summit, but progress in negotiations is likely.
The two leaders will agree to have their countries jointly produce mixed rare earth minerals and metals, key elements in defence industry components and modern technology.('Eagerly Waiting for Your Arrival': Japan's Shinzo Abe to Narendra Modi)
Mr Modi and host Prime Minister Abe are also expected to strengthen defence ties, speeding up talks on the sale of an amphibious aircraft to the Indian navy.