Since the Dec. 14 massacre of 20 children and six adults at Sandy Hook Elementary School in Newtown, Connecticut, calls for stricter gun control are gaining momentum in the United States.

To support the move, Mieko and Masaichi Hattori, whose son, Yoshihiro, was gunned down at age 16 in Baton Rouge, Louisiana, in 1992, have written to U.S. President Barack Obama in English, urging him to "listen to the voices calling for (stricter) gun control."

Last October, on the 20th anniversary of their son's death, Hattori and her husband, both 65, made a speech at a memorial ceremony in Baton Rouge.