Where to buy Plarail in Japan?

I've been in Japan for a few days and it surprised me to see Plarail stores not fully stocked with the whole range of items. In particular I was looking for a large station with a large control panel, however I didn't find this at the main Plarail shops at both Tokyo station and the Skytree town.

In short I'm just wondering if theres a good place to get plarail in Osaka since I'm going there soon