"The player's qualities were taken into account, we signed him for his qualities as a player and as a scorer."
The Toulon boss said that Goromaru would have his work cut out as he competes with Wales star Leigh Halfpenny for a fullback place.
"He'll be competing against Leigh Halfpenny for the back post. Ayumu is a player who can be decisive, above all when Leigh is absent during the Six Nations and the November series," he said.
"We're very happy to have signed him. We spotted him during the World Cup against South Africa, a match which marked a turning point in world rugby. It's the new rugby. Japan have become a major nation in this sport."
After the World Cup, Goromaru left his club Yamaha Jubilo to play Super Rugby with Queensland Reds in Australia, but he played just eight games.
"When I played in Japan it was almost guaranteed for me to play at back," the player explained.
"In Australia there was more competition and I wasn't at all known. But in this environment, with this rivalry it was refreshing for me. I can't wait to experience this challenge again here." After the traditional medical, Goromaru, who is recovering from a right shoulder injury, will head back to Japan before returning for the new season in September.
Toulon, who were edged by Racing 92 in the European Cup quarter-finals, take on their rivals again in the Top 14 final in Barcelona on Friday.