<page_title> Tobu 50000 series </page_title> <section_title> 50050 series </section_title> <table> <cell> 2006 <col_header> Year built </col_header> </cell> <cell> 51051–51060 <col_header> Set numbers </col_header> </cell> </table>
The first set 51051 entered service in 2006.