The rooftop-like space of Minatogawa Station is actually a large park, encompassing the clock tower and the statue of Daikoku-ko.
Looking at the photos of Minatogawa Station, it might seem at first glance that the park is on the rooftop of the station building. However, there's a shopping street on the left side of the photos, and the end of the shopping street leads to a gradually ascending slope. At the top of the slope, exiting the other end of another shopping street, you'll find Minatogawa Park, which is actually on the ground level.
Both Minatogawa Station and Minatogawa Park are at ground level – it can be a bit confusing… but don't worry!