日本新党
In 1992, Sakihito joined the Japan New Party under Morihiro Hosokawa. During Morihiro's tenure, Sakihito served as a policy advisor. After Mohiro's resignation and the collapse of the JNP, Sakihito joined New Party Saigake. Two years later, Sakihito contested a seat within the Southern Kanto PR block, Sakihito won the seat and entered the diet. Sakihito joined the Democratic Party of Japan in 1998. During the late 90s, Sakihito held numerous positions within the DPJ, including Deputy Secretary General and Director of the Policy Research Council.