First Chapter (前編, Zenpen) is the first installment of Kamen Rider Build: Raising the Hazard Level ~7 Best Matches~. It features the debut of Build's SmaphoWolf Hazard Form. Similar to Kamen Rider Ex-Aid "Tricks": Kamen Rider Genm before it, it showcases the Fullbottles from Hokuto and the Hokuto Best Matches. This chapter takes place immediately after Sento obtains the Fullbottles from Hokuto and Seito in Episode 21, but one week prior to the scene where Build charges at Grease at the proxy due