Craig grew up in Maryland and became a Christian during high school. After college, he taught high school math and computer science for seven years, then worked as a computer programmer for five years.

Ree was born in Delaware, grew up in Maryland, and became a Christian during college. She has a bachelor's degree in Russian and a master's degree in teaching English as a second language.

During summer 1987 in Japan, Craig and Ree saw the great need for the gospel to be preached in that land, where only 1/3 of 1% are evangelical Christians. God gave them a desire to be part of bringing the gospel to Japanese people, and they returned to Japan as MTW missionaries in 1994.

The Coulbournes have been a part of outreach to Makuhari Bay Town in Chiba City since 1996, and saw God bring Kaihin Makuhari Grace Church into existence in 2001. Criag and Ree minister at Makuhari through evangelistic Bible studies, discipleship of young believers, and identifying and training future leaders.

Daniel (5/1/91), Hannah (10/31/93), Mary (8/23/95), Andrew (1/27/04)