Kairi’s connection with Naminé is the most essential in her role, seeing how she is the origin of Naminé's existence. She is where Naminé originated from when Kairi’s heart was taken away by the heartless. Naminé and Kairi are one and the same because she is Kairi’s other half, her nobody. When your heart is taken away, you turn into a heartless, but for a princess of heart you still attain your original body. This is what happened to Kairi that is why Naminé’s powers are different compared to the rest of the Organization XII.

The only in-game interaction these two actually have is at the last world of Kingdom Hearts II, The World That Never Was. When Kairi was locked up in the castle by Saïx, Naminé frees her from the prison. Kairi was soon reunited with Riku, and we don’t hear anything about Naminé again until At the Alter of Naught near the ending of the game. This was when Naminé merged with Kairi, making the two of them whole.