>>280101564
How the hell did you pass N1 without any practice speaking or writing? I don't think it tests on those but it's a common way to reinforce vocab and grammar. What were you doing to retain that much without utilizing it?
Your best bet is probably just to hire a private tutor for weekly calls and writing assignments. It'll get rid of the anxiety since their whole job is to help people like you, they know where you're at. That or you could just go to Japan and visit a bar. People are there to talk to each other and four beers or so will calm the nerves. That's where most of my speaking practice comes from.