お互いの正体が仮面ライダーである事を知ったショウマと絆斗。 しかし、グラニュートに恨みを持つ絆斗に、ショウマは自分もグラニュートである事を打ち明けられなかった。 その頃、失態を重ねストマック社をクビになったシータとジープは、拠点を追い出され露頭に迷う羽目になる。 怒りの矛先は全てショウマに向けられ、自らの手でガヴを始末するため動き出す。 そんな危機的な事態を露知らず、ショウマは幸果と共にクリスマスのケーキづくりをすることに。 ショウマにとってケーキは特別な思い入れのあるものだった。
Shoma and Kizuna discover that each other's true identities are Kamen Riders. However, Shoma was unable to confide in Kizunato, who had a grudge against Granut, that he was also Granut. At that time, Sheeta and Jeep, who were fired from the Stomach company due to their failures, are kicked out of their base and end up getting lost on an outcrop. All of his anger is directed at Shoma, and he sets out to eliminate Gav with his own hands. Unaware of this dangerous situation, Shoma decides to make a Christmas cake with Yukika. For Shoma, cake was something that had a special meaning.
