If flow is so important, then why aren't we starting with Japanese? I'm not fluent in English.

[Near-fluent, but not perfectly so. And he can understand it far better than he can speak it himself. Though perhaps that's the point, that learning the pronunciation in a language you're unfamiliar in helps make sure you do it properly. In fact, a moment later, Watanuki decides to put that thought to words.]

Is it because it's a second language, so I pay more attention while speaking it anyway?