Japan Rugby League One chairman Genichi Tamatsuka said the games involving New Zealand DHL Super Rugby Pacific sides the Blues and Chiefs resulted in four entertaining games.
He said, "There were good results for both countries, which added to the competitive element of the series."
Japan's Saitama Panasonic Wild Knights achieved the first win for their country when beating the Chiefs, while Kubota Spears Funabashi Tokyo Bay ended within five points of the Chiefs in their second game.
"The effort of the Wild Knights in beating the Chiefs was not just a proud achievement for the club; it was also a significant moment for rugby in Japan as a whole.
"It was a statement that Japanese club teams can compete with their international counterparts, a further sign of the growth in the playing level that we are achieving through Japan Rugby League One."
He said the timing of the competition was not ideal, but the concept was only the beginning, and the opportunity for a more formal series was something for the future.
"That is our ultimate objective, but everything must start somewhere. We now have something to build on."