| Name | In-House Group | Constituency/Area |
|---|---|---|
| IBAYASHI Tatsunori | LDP | Shizuoka 2nd District |
| ICHIMURA Koichiro | JIP | Kinki Bloc |
| ICHITANI Yuichiro | JIP | Kinki Bloc |
| IDE Yosei | LDP | Nagano 3rd District |
| IDO Masae | DPFP | Tokyo Bloc |
| IGARASHI Kiyoshi | LDP | Tochigi 2nd District |
| IHARA Takumi | LDP | Ehime 2nd District |
| IHARA Yutaka | LDP | Saitama 5th District |
| IIZUMI Kamon | DPFP | Shikoku Bloc |
| IKEHATA Kotaro | JIP | Kinki Bloc |
| IKESHITA Taku | JIP | Osaka 10th District |
| IMAEDA Soichiro | LDP | Aichi 14th District |
| IMAOKA Ueki | LDP | Tokyo 26th District |
| INABA Daisuke | LDP | Shizuoka 8th District |
| INADA Tomomi | LDP | Fukui 1st District |
| INO Toshiro | LDP | Gunma 2nd District |
| INOUE Hidetaka | JIP | Osaka 1st District |
| INOUE Shinji | LDP | Tokyo 25th District |
| INOUE Takahiro | LDP | Fukuoka 1st District |
| INUKAI Akiyoshi | CRA | Tokai Bloc |
| ISA Shinichi | CRA | Kinki Bloc |
| ISHIBA Shigeru | LDP | Tottori 1st District |
| ISHIBASHI Rintaro | LDP | Hiroshima 3rd District |
| ISHIDA Masatoshi | LDP | Kinki Bloc |
| ISHIHARA Hirotaka | LDP | Tokyo 3rd District |
| ISHIHARA Masataka | LDP | Mie 3rd District |
| ISHII Keiichi | Ind | Kita Kanto Bloc |
| ISHII Taku | LDP | Aichi 13th District |
| ISHIKAWA Akimasa | LDP | Kita Kanto Bloc |
| ISHIKAWA Masaru | SAN | Kinki Bloc |
| ISHIZAKA Masaru | LDP | Tochigi 4th District |
| ITO Keisuke | SAN | Tokai Bloc |
| ITO Nobuhisa | JIP | Kinki Bloc |
| ITO Satoshi | LDP | Minami Kanto Bloc |
| ITO Shintaro | LDP | Tohoku Bloc |
| ITO Tadahiko | LDP | Aichi 8th District |
| ITO Tatsuya | LDP | Tokyo 22nd District |
| ITO Yoshitaka | LDP | Hokkaido Bloc |
| IWASAKI Hina | LDP | Minami Kanto Bloc |
| IWATA Kazuchika | LDP | Saga 1st District |
| IWATANI Ryohei | JIP | Osaka 13th District |
| IWAYA Takeshi | LDP | Oita 3rd District |
| IZUMI Kenta | CRA | Kyoto 3rd District |
Notes:
List of the In-House Groups in the House
District: Single-seat constituency
Bloc: Proportional representation area
In-House Group: A group of House Members who engage in joint activities within the House. Usually, a political party forms an in-House group inside the House, but occasionally there are cases where a group is formed by (1) House Members who do not belong to a particular political party, (2) a political party and a House Member or Members who do not belong to any political party, or (3) two or more political parties.