Kamen Rider Ryuki

In 2002, Japan experienced a series of strange cases of missing people. Journalist Shinji Kido investigated one of the victims, Koichi Sakakihara, and during his investigation at Sakakihara's home, he discovered a card box. Later, Shinji accidentally used the power of the card box to transform into Kamen Rider Ryuki and met another Rider, Ren Akiyama (Kamen Rider KNIGHT), and Shirou Kanzaki's sister, Yui Kanzaki. Shinji's goal as a Rider was to protect humanity and prevent conflicts between Riders, while Ren, who disliked fighting, was forced to battle with other Riders to save his loved one. As other Riders appeared, battles gradually intensified, and despite Shinji's desperate attempts to stop them, casualties continued to rise. As the conflict between Riders escalated, Shinji discovered that Shirou Kanzaki had initiated the battles to save Yui. It turned out that Yui had died in her childhood, and her life was being sustained by a version of Yui from the Mirror World, which would only last until she turned 20, after which she would disappear. Knowing this, Shirou Kanzaki wanted to give Yui the last remaining life of a Rider, hence instigating battles among them. Shinji realized that the only way to save Yui was to fight, forcing him to choose between stopping the battles and saving Yui. On the other hand, Yui, aware of her brother's intentions, was willing to give up her new life to prevent the battles and ultimately disappeared before Shirou. Influenced by Yui, Shinji decided to continue fighting to protect humanity, but unfortunately, he was severely injured and died while trying to protect a girl from a monster. Ren became the last Rider and succeeded in awakening his loved one but eventually died from his injuries. After the battle, Shirou Kanzaki returned to the past, initiating the Rider battles again but was stopped by Yui. In the end, Shirou returned to the past, ensuring no battles between Riders would occur, allowing everyone to lead ordinary lives, while Yui had already died in her childhood.