Half of the 242 seats in the upper house are up for grabs every three year under the combination of constituencies and proportional representation, while about 430 candidates are expected to compete for the 121 rotating seats this time.

　　The ruling Liberal Democratic Party (LDP) head by Prime Minister Shinzo Abe, along with its ruling ally the New Komeito Party, has to secure 63 seats to win a majority in the chamber, as they already hold 59 seats that will not be contested this time.

　　As of now, the opposition parties remain the majority in the upper house, with the largest party in the chamber, the Democratic Party of Japan, holding 86 seats, making the Japanese Diet a divided parliament as the ruling camp has an overwhelming majority in the more powerful lower house.

　　The upper house election is set to start on July 21 and the leaders of the political parties will hit streets to call for supports in the 17-day campaign period.