Katsuragi Takumi was the founder of Faust! Sento and Ryuga are frozen by these words that Blood Stalk just revealed to them. A fearsome power may be at work behind the murder of Katsuragi Takumi. And this is mostly because Build’s lost memories are involved. There is a sign that secret data entrusted to his mother by Katsuragi might be a clue. While talking to Katsuragi’s mother, these two become certain that this data collection exists. The fight between Build and Faust arises once again over the existence of this mysterious data… (Source: kamenrider.fandom)