The Mass was said by Nagasaki Archdiocese Secretary-General Kosera Akira, and Croatian Ambassador Drago Stambuk addressed those attending the event.
According to the statement, Akira spoke about the suffering of Vukovar and the need for mutual understanding among people who have experienced similar suffering.
Stambuk recalled that requiem Masses for Vukovar victims had so far been said in Nagasaki in 2006, 2009 and 2010, in Hiroshima in 2007 and in Tokyo in 2008.
In attendance at the religious service were several hundred people, including Nagasaki Mayor Tomihisa Taue, members of the Nagasaki-Croatia Friendship Society, and Japanese member of parliament Seigo Kitamura.
Prayers were said for Vukovar in all churches of the Archdiocese of Nagasaki on Sunday.