Miyoko Watai, 59, is the acting president of the Japan Chess Association and involved in a romantic relationship with Fischer, 61, the New York Times reported Friday.
"I could be a sacrifice pawn," she said. "But in chess, there is such a thing as pawn promotion, where a pawn can become a queen."
Fischer's lawyer said the engagement formalizes an authentic bond of love that has already been established between Fischer, a former world chess champ, and Watai, a four-time woman's chess champion in Japan.
"It was a de facto marriage; we are now making it a legal marriage," lawyer Masako Suzuki said. "I have never seen a case where there is this passion and devotion."
Fischer was detained July 13 because the United States ordered the revocation of his passport in December.
Putin thinks Obama would save him if he were drowning
Chipotle plans first price increase in 3 years