Love Come Manga ni Haitte Shimatta node, Oshi no Make Heroine wo Zenryoku de Shiawase ni Suru

After an inexplicable twist of fate, a devoted fan finds himself transported directly into the pages of a wildly popular romantic comedy manga. However, he does not awaken as the dashing protagonist destined to win the girl's heart. Instead, he inhabits the body of the male lead’s best friend—a supporting character traditionally relegated to the sidelines. Despite this unexpected role, he quickly realizes that his new reality offers something far more valuable than a leading part: the unprecedented opportunity to rewrite the tragic narrative of his absolute favorite character. Sei-chan, the beloved "losing heroine" whose unrequited feelings were always destined to end in heartbreak, is now someone he can actually reach. Armed with intimate knowledge of the story and a fierce determination to change her fate, he resolves to pour every ounce of his effort into ensuring she finally experiences true joy. Casting aside his minor role in the original plot, he approaches her with a heartfelt and earnest confession, promising to give her all the happiness she has always deserved if she will only agree to go out with him. Caught completely off guard by his sudden sincerity, Sei is left stunned, questioning whether his bold declaration could possibly be real.