Board Thread:General Discussion/@comment-78.160.126.18-20131214130111/@comment-4503347-20131214190759

Official guidebook of Ace Combat 04 confirms Nagase from Ace Combat 04 is Kei Nagase in Ace Combat 2. This is mentioned in articles Kei Nagase and in Kei Nagase (AC2). The one in Ace Combat 5 is unrelated.

If you want evidence, here it is, under "ケイ・ナガセ" at the bottom left.