The Wiki admits that those projects up to at least 2005 required international collaborators (NASA).
Where does Wikipedia admit that NASA collaboration was required for those projects? How do you know which projects NASA collaborated on and which ones were entirely Japanese home gown?
Well, they plainly admit that their projects are mainly led by NASA on their website.
See the bolded below:
http://global.jaxa.jp/activity/int/International cooperation between the United States and Japan started in 1969, when "The Japan-U.S. Joint Communique" on cooperation in space development was exchanged. Since then, JAXA has been participating in international projects, which have been mainly led by the National Aeronautics and Space Administration (NASA)
The JAXA wiki clearly states that the projects up until at least 2005 were international projects. Now this page is saying that the international projects were mainly led by NASA.
Therefore we see that, surprise surprise, NASA has been leading JAXA space projects.