The House of Councillors by-elections were won by one LDP-Kōmeitō supported candidate (Aiko Shimajiri in Okinawa) as replacement for OSMP Councillor Keiko Itokazu, and one Democrat (Teruhiko Mashiko in Fukushima) as replacement for Democrat Yūhei Satō, producing a net gain of one seat for the ruling centre-right coalition three months before the regular House of Councillors election of 2007.