Under the then prime minister Koizumi, he served in a number of positions, including the Financial Reconstruction Commission, the National Public Safety Commission, and ultimately as Minister of Finance from 22 September 2003 to 26 September 2006.
Dibawah kepemimpinan perdana menteri Koizumi, ia menjabat dalam sejumlah jabatan, yang meliputi Komisi Rekonstruksi Keuangan, Komisi Keselamatan Publik Nasional, dan Menteri Keuangan dari 22 September 2003 sampai 26 September 2006.