March is the end of an academic year and the season for farewell. Words of encouragement sent by successful alumna present the perfect send-off for students lined up at graduation ceremonies.

But one such message supposedly sent by famous singer-songwriter Miyuki Nakajima to her alma mater, Obihiro Hakuyo High School in Obihiro, Hokkaido, turned out to be a prank, according to the school and her agency.

The false message, which contained general words of encouragement and nothing unusual, was read aloud at the school's graduation ceremony Sunday. It had been faxed to the school on Saturday, school officials said.

The school admitted it didn't confirm the authenticity of the message. Local media who were reporting on the graduation ceremony inquired with Nakajima's agency and learned the message was false.

School Principal Katsunori Nakanishi said he regrets not confirming the message. "I feel sorry for the graduating students," he said.

Nakajima rose to fame with the 1977 hit "The Parting Song" ("Wakareuta"). Four of her singles have sold more than 1 million copies in the past two decades, including "Earthly Stars (Unsung Heroes)," the theme song for the NHK documentary series "Project X."