The Little Dark Magician Girl - By the start of the story, Seto and Kisara are already a couple, and they both help everyone else against Vivian when she turns into the Mythic Dragon.
Kisara and the Beast - When Kisara confesses her love for Kaiba when he dies from rapid blood loss, Ishizu restores his true form of Seto, and she also restores his life. After convincing Kisara that it was him, the two get married.
Yu-Gi-Oh! Beauty and the Beast 3.0 - When Kisara confesses her love for Kaiba when he dies from rapid blood loss, Ishizu restores his true form of Seto, and she also restores his life. After convincing Kisara that it was him, the two get married.
Yu-Gi-Oh! High School Musical 3.0 - Seto and Kisara meet on New Years Eve and end up being drafted into a singing contest. Afterwards, Seto's found out that Kisara's been transferred to Domino High. After talking with Kisara, they end up watching the auditions for the winter musical, and when Serenity ends up being bullied by Mai, Seto and Kisara encourage her, so Serenity shows them how the show was originally supposed to go. They then end up with a call-back when they sing the song while the director/theater teacher, Rebecca hears. The whole school turns topsy-turvy when they hear, and Kisara and Seto's friends both team up to break the two up. They bag on Seto until he says what they want to hear to shut them up, and they rig it, so Kisara hears. Kisara then breaks up with Seto until Seto explains things to her, so they, with their friends' support, do their call-back and get the parts. The two then party with the rest of their friends.
Yu-Gi-Oh! Beauty and the Beast (Vase) - Before the curse was cast upon them, Seto and Kisara already had mutual feelings of friendship and attachment but over the years as they waited for a girl to come and show Prince Atem what love was, their own feelings grew into love and after the spell was broken, Seto caught Kisara, who had been about to fall from the disorientation of being fully human again.
Yu-Gi-Oh! Beauty and the Beast - After Kaiba dies from his wounds, Kisara proclaims her love for him and the Dark Magician Girl appears to lift the curse. Kaiba transformed into his true self, Seto and his life was also restored. They live happily after Seto assures Kisara it's still him.