Surya Kumar Bose, who lives in Germany, left for Tokyo where he would meet family members of the people who knew Netaji or had worked with him.
In a statement here, Surya K Bose said, "I am looking forward to visiting Japan which had played such a key role in the final battle for Indian Independence led by Netaji, popularly known as Chandra Bose in Japan."
During his week-long stay, he would seek the help of Japanese government in declassifying the remaining documents which could throw light on Netaji's fate as well as the history of Indian National Army.
When under house arrest by the British, Netaji had escaped from India in 1941 to seek international support for India's freedom struggle.
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After organising the Indian National Army with Japanese help he went missing in 1945, giving birth to India's most debated mystery.
After his 'cremation' near the crash site, his 'ashes' were taken to the Renkoji Temple in Japan.
"We are also trying to ascertain whose ashes are kept there and from where it came," Chandra Kumar Bose, a member of the Bose family here said.