An unknown man who phoned the Daiei Hawks said that team manager Sadaharu Oh will have to pay cash if he wants his wife's stolen ashes returned.
The ashes of Kyoko Oh were stolen from her grave last year, and police have so far failed to crack the case.
"If Oh wants the ashes back, pay money," the man was quoted by police as saying, demanding 3 million yen in a call to the Hawks after the team won the Japan Series on Oct. 27.
The caller tried to talk directly with Oh, but the Hawks refused. Police are trying to verify if the caller was the actual grave robber.
Oh, 63, the all-time home run leader in Japanese baseball with 868 career homers, told Kyodo News, "I will just wait for the next contact. I have no idea and cannot understand the reasoning of a person who steals ashes."
Kyoko Oh died of stomach cancer in 2001 at age 57. Her ashes were believed stolen last December from the family grave at a temple in Meguro Ward, Tokyo.
Grave robbery carries a penalty of up to five years in prison.