"It is with great pleasure and excitement that I am coming for the first time to Japan," said the 24-year-old Spaniard, who won his fifth French Open title this month and is limbering up for Wimbledon.
"To me, this is a great opportunity to play in a tournament that I have never played before and that I have heard great things from other players. I know I have a huge fan base in Japan so that also makes me very happy."
Organizers said that defending champion Jo-Wilfried Tsonga of France, his compatriot Gael Monfils, American Andy Roddick and Lleyton Hewitt of Australia would also compete in the October 4-10 hardcourt tournament in Tokyo.
Local hope Kei Nishikori, one of only two Japanese men who have won an ATP title, will be back after missing last year's event due to an elbow injury.
"It's always special for me to play in Japan. I've heard that Nadal will take part in the tournament. I'm really looking forward to play against him," said Nishikori, 20.