Prosecutors on Friday raided locations linked to the Japan Aerospace Exploration Agency (JAXA) after arresting a senior education ministry official earlier on a bribery charge.
The graft scandal is the second to hit the education ministry in a month.
Kazuaki Kawabata, the ministry's former director-general for international affairs, was arrested Thursday on suspicion of taking bribes in the form of wining and dining to a former consultancy executive in return for a favor.