According to Sports Hochi, Ichinoseki had an MLB tryout last Autumn, but failed. He wound up in Belgium in a Web 2.0 kind of way: an agent his college manager knew posted video of him throwing to a website, and Namur saw it and asked for more video. The team liked what it saw and signed him.
I know very little about Belgium's baseball league, but its level of play is reputedly lower than the leagues in Italy and the Netherlands. Another fun fact is that Leon Boyd played there prior to getting his Dutch passport and joining the Honkbal Hoofdklasse. Mister Baseball has a brief recap of Namur's 2009 season here.
Ichinoseki says his goal is to return to Japan and play in NPB. He's well off the beaten Industrial League / Independent League path, so whatever he winds up he'll have taken a unique route.