"In general we started well and played dynamically in the opening stages," the 61-year-old told reporters.
"As for what happened, Ivory Coast increased their strength and were able to beat us. It was true in the last 20 minutes of the first half as well but we weren't able to attack them enough.
"We let them attack us when we should have played more aggressively. We gave their players too much space and didn't play well defensively or offensively. Ivory Coast won because they had space. Normally we can play quickly but we gave them too much room."
Japan are next in action against Greece on June 19.