Question: What is the seat of the county that includes Belle Plaine, Kansas?

full_context: Document 1: Sumner County, Kansas: Sumner County (standard abbreviation: SU) is a county located in the U.S. state of Kansas. As of the 2010 census, the population was 24,132. Its county seat is Wellington.
Document 2: Johnson County, Kansas: Johnson County (county code JO) is a county located in the U.S. state of Kansas. As of the 2010 census, the county population was 544,179, making it the most populous county in Kansas. Its county seat is Olathe, and its most populous city is Overland Park.
Document 3: Kansas City, Kansas: Kansas City is the third-largest city in the state of Kansas, the county seat of Wyandotte County, and the third-largest city of the Kansas City metropolitan area. Kansas City, Kansas is abbreviated as "KCK" to differentiate it from Kansas City, Missouri. It is part of a consolidated city-county government known as the "Unified Government". Wyandotte County also includes the independent cities of Bonner Springs and Edwardsville. As of the 2010 census, the city had a population of 145,786 residents. It is situated at Kaw Point, which is the junction of the Missouri and Kansas rivers.
Document 4: Belle Plaine (community), Wisconsin: Belle Plaine is an unincorporated community located in the town of Belle Plaine, Shawano County, Wisconsin, United States. Belle Plaine is 5.5 mi south-southwest of Shawano.
Document 5: Sedgwick County, Kansas: Sedgwick County (county code: SG) is a county located in the U.S. state of Kansas. As of the 2010 census, the population was 498,365, making it the second-most populous county in Kansas. The county seat is Wichita, the most populous city in the state.
Document 6: Belle Plaine Main Street Historic District: The Belle Plaine Main Street Historic District is a nationally recognized historic district located in Belle Plaine, Iowa, United States. It was listed on the National Register of Historic Places in 2013. At the time of its nomination it contained 63 resources, which included 46 contributing buildings, one contributing structure, and 16 non-contributing buildings. The historic district covers most of the city's central business district. Belle Plaine was laid out in 1862 as a railroad town. The Chicago & North Western Railroad was extended from Cedar Rapids the following year. The commercial district is adjacent to the tracks. A major fire destroyed much of the business district in 1894. Thirty-five buildings in the district were built in the months after the fire.
Document 7: Pottawatomie County, Kansas: Pottawatomie County (standard abbreviation: PT) is a county located in the U.S. state of Kansas. As of the 2010 census, the county population was 21,604. The county seat is Westmoreland. The county takes its name from the Potawatomi tribe of Native Americans.
Document 8: Lee's Summit, Missouri: Lee's Summit is a city located within the counties of Jackson (primarily) and Cass in the U.S. state of Missouri. As of the 2010 census its population was about 91,364, making it the sixth-largest city in both the state and in the Kansas City Metropolitan Area. In 2006, CNN/Money and "Money" magazine ranked Lee's Summit 44th on its list of the "100 Best Cities to Live in the United States." That ranking improved to 27th on the 2010 list.
Document 9: Merriam, Kansas: Merriam is a city in Johnson County, Kansas, United States, and part of the Kansas City Metropolitan Area. As of the 2010 census, the city population was 11,003. It is bordered by the cities of Overland Park to the east and south, Shawnee to the west, and Kansas City, Kansas to the north (in Wyandotte County); the city of Lenexa is less than a mile to the southwest. Merriam is included in the Shawnee Mission postal designation.
Document 10: Belle Plaine, Wisconsin: Belle Plaine is a town in Shawano County, Wisconsin, United States. The population was 1,867 at the 2000 census. The unincorporated communities of Adams Beach and Belle Plaine are located in the town. The former unincorporated community of Hunting was located partially in the town.
Document 11: Lincoln County, Kansas: Lincoln County (standard abbreviation: LC) is a county located in the U.S. state of Kansas. As of the 2010 census, the county population was 3,241. The largest city and county seat is Lincoln Center.
Document 12: Belle Plaine, Kansas: Belle Plaine is a city in Sumner County, Kansas, United States. As of the 2010 census, the city population was 1,681.
Document 13: Wallace County, Kansas: Wallace County (standard abbreviation: WA) is a county located in the U.S. state of Kansas. As of the 2010 census, the county population was 1,485, making it the second-least populous county in Kansas. Its county seat is Sharon Springs. The county was created in 1868 and named in honor of Brigadier general W.H.L. Wallace who was a veteran of the Mexican-American War and a casualty of the Battle of Shiloh.
Document 14: Wyandotte County, Kansas: Wyandotte County ( ; county code WY) is a county located in the U.S. state of Kansas. As of the 2010 census, the population was 157,505, making it the fourth-most populous county in Kansas. Its county seat and most populous city is Kansas City, with which it shares a unified government. Wyandotte County lies immediately west of Kansas City, Missouri.
Document 15: Belle Plaine, Saskatchewan: Belle Plaine is a village in the rural municipality of Pense No. 160, in the Canadian province of Saskatchewan. Belle Plaine is located on Highway 1 or the Trans Canada Highway 21 kilometers east of Moose Jaw in south central Saskatchewan. Buffalo Pound Provincial park and Regina Beach are located near Belle Plaine. This village had a population of 64 according to the municipality. The 2006 census enumerated this location with the R.M. of Pense No. 160.
ground_truth: Wellington