Japan withdrew Tuesday because of problems forming a team following March's earthquake and tsunami.
Costa Rica will send a team of players mostly under 23, with five older players.
"We are not just going to take part, we want to play a good role," Costa Rica federation president Eduardo Li said. "We firmly believe going to the Copa America is important."
Costa Rica and Mexico are invited guests to the tournament, which will be held in Argentina from July 1-24.