Myanmar leader Aung San Suu Kyi this week sent a letter of condolence to the widow of a Japanese Foreign Ministry official who died in a knife attack in Kawasaki, the president's office said Friday.

(Photo taken April 13, 2013, shows then Myanmar opposition leader Aung San Suu Kyi (R) arriving at Narita airport near Tokyo for a weeklong visit, with Japanese Foreign Ministry official Satoshi Oyama (L) attending.)

In the letter dated Wednesday and released to Japanese media, Suu Kyi wrote she was "shocked and saddened" by the death of Satoshi Oyama, a Burmese-language specialist she met during her visit to Japan in April 2013.

Oyama "impressed us all with his linguistic skills as well as his gentle, friendly nature," she wrote. "Japan has lost a good diplomat who made a valuable contribution to the friendship between our countries."

Oyama and an 11-year-old girl were killed in the attack Tuesday, while 17 others, mostly children, were injured. The motive of the assailant, who committed suicide, remains unclear.