The Indo-Japanese nuclear deal has been six years in the making. After prolonged negotiations, Japanese Prime Minister Shizo Abe and his Indian counterpart Narendra Modi will sign a civil nuclear cooperation during Modi's visit to Tokyo on Friday, November 11.

The deal will mark Japan's first nuclear cooperation agreement with a country that is not a signatory to the nuclear non-proliferation treaty (NPT). The NPT is an international treaty meant to prevent the spread of nuclear weapons and arms technologies, while promoting the peaceful use of nuclear energy. India refuses to sign it, saying it is discriminatory because it defines nuclear-weapons states as those that tested nuclear devices before 1967.

The nuclear deal between Asia's second and third largest economies has been described by the two countries as "a new level of mutual confidence and strategic partnership for the cause of a peaceful and secure world."

Supporters of the impending deal say it is a win-win situation for both Tokyo and New Delhi. India will be able to feed its energy-hungry economy with emission-free energy, whereas Japan opens up new business opportunities for its nuclear sector.

Japan's cutting-edge nuclear technology is considered crucial for India's massive economic growth. Japan has a monopoly in the manufacturing of reactor safety components and power plant domes - key parts that India needs to enable its nuclear cooperation programs with the US and other countries.

The deal would allow Japan's struggling nuclear industry access to the growing Indian market, which is estimated to be worth $150 billion. This would be a great opportunity for Japanese nuclear companies that have suffered greatly since the 2011 Fukushima nuclear accident.

India's similar civil nuclear deals with South Korea and the US "have boosted bilateral relations," Smruti Pattanaik, a research fellow at the New Delhi-based Institute for Defense Studies and Analyses, told DW.

But concerns remain about India's potential misuse of the technology for developing more nuclear weapons. The Japanese people have long been apprehensive about the deal with India due to its nuclear weapons program.

"The Japanese government has softened its stance for the sake of economic benefits," Akira Kawasaki of Tokyo-based Peace Boat organization, told DW. "The deal grants the same rights de-facto to India as other nuclear powers that have signed the NPT."

The shift in Japan's nuclear cooperation policy with India started in 2008, when the Nuclear Suppliers Group (NSG) granted a waiver to New Delhi to push through a civil nuclear agreement with Washington. NSG - a 48-nation grouping that includes the US, Russia, Britain, France and Japan - controls the export of nuclear technology and materials to prevent the proliferation of nuclear weapons.