|This article is about a/an web episode in Kamen Rider Zi-O.|
Supplementary Plan Forever (Part I) (補完計画よ永遠に(前編) Hokan Keikaku yo Eien ni (Zenpen)) is the fifteenth and penultimate episode of Kamen Rider Zi-O: Supplementary Plan. It was released on TTFC accompanying the fifteenth episode of Kamen Rider Zi-O, as well as the film Kamen Rider Heisei Generations FOREVER, as its "episode 15.5".
- Sougo Tokiwa (常磐 ソウゴ Tokiwa Sōgo): So Okuno (奥野 壮 Okuno Sō)
- Geiz Myoukouin (明光院 ゲイツ Myōkōin Geitsu): Gaku Oshida (押田 岳 Oshida Gaku)
- Tsukuyomi (ツクヨミ) : Shieri Ohata (大幡 しえり Ōhata Shieri)
- Woz (ウォズ Wozu): Keisuke Watanabe (渡邊 圭祐 Watanabe Keisuke)