SempySempy is a commune in the Pas-de-Calais department in the Hauts-de-France region of France.GeographySempy is located 4 miles southeast of Montreuil-sur-Mer on the D129 road, alongside the banks of the small Bras de Bronne river.Places of interest The church of St. Firmin, dating from the thirteenth century Traces of an ancient chateau. A watermill and a windmill.