Japan House of Councillors election (July 20, 2026): Sanseito wins at least 6 of the 125 newly contested seats

In Japan's upper house election on July 20, 2026, the right-nationalist Sanseito party is poised for significant gains according to CSIS analysis and Nippon.com ('smaller parties making gains in a fragmented landscape'). Sanseito held roughly 8–9 total seats after 2022. Issues such as immigration criticism, loss of purchasing power, and LDP fatigue mobilise the nativist electorate. A net gain of ≥6 of the 125 newly contested seats is plausible given the political climate and the expected loss of the LDP-Komeito coalition majority (open platform prediction). No direct Polymarket equivalent for Sanseito seats.