Kenseito was one of the two main Japanese political parties before World War Two in the Pacific, and the dissolution of parties in 1940. There are various translations of the name; Constitutional Party is common. The group was considered relatively more liberal than Seiyukai in that it stressed constitutional structure, although neither could be considered liberal in a Western sense.
Shigenobu Okuma and Taisuke Itagaki cofounded it in 1898. It soon split into factions, the members of the old Liberal Party retaining the Kenseito , and the old Shinpoto (Progressive Party) faction calling itself the Kensei Honto (Real Constitutional Party). Nevertheless, Kenseito did produce working cabinets. 
- 2-18 Birth of the "Waihan" (OKUMA-ITAGAKI) Cabinets, National Diet Library