The Japanese Wife story revolves around a young village school teacher (Rahul Bose) marrying his Japanese pen friend (Chigusa Takaku) over letters and remaining true and loyal to her throughout his life, while actually never meeting her.
Snehmoy (Rahul Bose) and Miyage (Chigusa Takaku) are pen friends who exchange wedding vows through letters. Fifteen years pass but they never meet. Yet the bond of marriage is strong between them. This unusual relationship comes under a cloud when a young widow, Sandhya (Raima Sen), comes to stay with Snehmoy along with her eight-year-old son (Rudranil Ghosh).
Snehmoy and the little boy bond and the arithmetic teacher discovers the joy of palpable bonds and fatherhood. There develops an inexplicable thread of understanding with Sandhya too.