GameFAQs’ TheWertle translated an interview from FF13Vids, who got it from the Japanese magazine “Dengeki PS” (電撃PS):

Question: Your debut as director was with Kingdom Hearts. What was the process of bringing that out like?

Nomura: With the designs of Kingdom Hearts, I had designed a plot around the time that Final Fantasy VII was in production, and by the time of Final Fantasy VIII, I had full out designs. But at that point the Disney characters hadn’t completely appeared. Shinji Hashimoto came up with the idea of a story with Disney. Since, at that time, Mr. Disney was in the same building, Hashimoto would sometimes talk with him on the elevator – And I guess they worked something out.

Question: Were you the director at that time?

Nomura: No. I was polishing up the Kingdom Hearts designs and thinking of what the next line of development would be. Someone else was appointed as the director for this “Disney game”. I think until then the things I did were often pretty useless. But the Kingdom Hearts team told me “We want you to participate with us Tetsu-san. No one else would make a better director“, and so they pushed for that afterwards.