If you are calling me a liar, I expect you to back down on that.
I am saying you did not corner him. You only thought you did. Based on my experience with Japanese bureaucrats, cornering one is about as likely as nailing jello to a tree.
Also, are you sure this was the minister, and not some sub-minister, some other MP, or a high muckety-muck from the ministry? The ministers are busy. As rule, they know nothing about the actual business of the ministry, and they do not show up for work. Except for the Finance and Foreign ministers, based on national news interviews and Sunday morning talk shows, I have the impression they know nothing and care nothing about their departments. They don't know much about energy or technology.
A high muckety-muck from the ministry would know a lot about energy.