User blog comment:Lordxehanort/Various Topics/@comment-1672596-20100207191419

Not quite certain about that, but I'm guessing he may have gone back to his Americanized name after Peace Walker due to a few reasons.

1. Japanese Americans were not exactly treated well during the seventies in America (Heck, most of them were still in Internment Camps, as it wasn't until the eighties that America apologized to the Japanese Americans for being treated like that, gave them money to start over, and closed down the internment camps.

and

2. he probably chose that name in order to try and disavow any ties to the events of Peace Walker.