In the alternate timeline presented in Cardfight!! Vanguard Gaiden if, the world is one where the protagonist Aichi Sendou never discovered the game of Vanguard, an absence that profoundly reshapes the lives of those connected to him. Within this context, Kai Toshiki is depicted as a loner, carrying a subdued and isolated personality. His characterization is stripped of the confident and rivalrous edge he displays in the main series, as the catalyst for their original bond and subsequent rivalry never occurs. The narrative of Gaiden if explores how this missed connection alters the dynamics between characters, particularly between Kai, Aichi, and Misaki Tokura. As the story progresses and Aichi inadvertently stumbles upon Vanguard cards, it sparks a chain of events that slowly reintroduces the characters to the game. For Kai, this process becomes a journey of gradual re-engagement with the world and others, highlighting how the card game serves as a medium for personal growth and connection even in this divergent reality. A key moment occurs when Kai encounters Takuto Tatsunagi and learns his true history, which leads to a meeting with Aichi, who is referred to as the master of Sanctuary. Regarding notable abilities within the Gaiden if series, detailed information on his specific skills as a cardfighter in this alternate timeline is not available.