After Reincarnating as the Ghost King's Twin Sister

【Updated daily at 6 p.m. The reading guide and upcoming title are below the blurb My Ideal Life Is Romance】 After transmigrating to the Heian period, Mirai discovers that in this world overrun by demons, she has also gained a sickly older brother. Just as she is training while trying to save her brother, a System suddenly appears and tells her that this world has a main quest. 【Attention: Your brother is about to become the thousand-year Demon King, the progenitor of demons. For the sake of world peace, your choice should be, 】 Mirai slaps the System away. “Come on, bro. I just ate the blue Spider Lily, so why not eat me? Or we can go one-on-one. Whoever wins becomes the Demon King... Bro, why are you running?” Muzan: She just slaughtered all the demons she met before. How could I not run?! Mirai's game of hide-and-seek with her Demon King brother ends in utter failure, and she can only keep working away at her System quest to become the 【Successor of the Gods】. Ever since becoming a demon, Mirai has been rather bad at reading other people's emotions, and she always feels like she's done a lot of things she ought to apologize for. She teamed up with the Nurarihyon to attack Osaka Castle, bringing the Sengoku era to an end and leaving the head of a certain samurai family completely out of a job. She found a brother and sister on the verge of death in the pleasure district, turned them into demons, then made them go to school. When the Wind Hashira was a child, she had his father thrown in jail, and couldn't even get him out afterward. She fought a wild boar in the forest, kidnapped “a pig,” then returned both the boar and “a pig” to his mother. Mirai pondered. “Would it still help if I apologized now?” The people Mirai thought she owed an apology to: ? A thousand years pass in the blink of an eye, and the System asks Mirai what she wants now. Mirai says, “I want the unreliable gods and my Demon King brother to accept my challenge. This time, whoever wins our duel to the death becomes a god.” Muzan: A chill ran down my back. The gods: A chill ran down my back x2. Muzan: “Why are you getting chills? Are you under more pressure than I am?!” 【Upcoming title, male-lead POV romantic spin-off: My Ideal Life Is Romance】 Story One: 【Demon General x Kikyo the Shrine Maiden】 As a great demon, Tsukimiya has no interest in humans at all, until he temporarily loses his demonic powers and reverts to his original form, a baby version of himself, and is accidentally adopted by the shrine maiden Kikyo. Kikyo often has to worry about whether this little kitten can survive when he can even singe his own fur while trying to warm himself by a fire. After Tsukimiya regains his human form, he returns to his territory. His deputy finally breathes a sigh of relief. “You're finally back. Which demon kingdom are we attacking next?” Tsukimiya ponders. “How do you think I should confess to that human shrine maiden so she'll say yes? Would all the territory I've conquered over the years be enough?” Deputy: “What are you talking about? A shrine maiden would only want to exterminate a great demon like you!” Tsukimiya: “If she wants to use me for practice, I don't mind. As long as I don't die.” “???” 【Story Two: Reiga x Vermouth】 Reiga has the power to live forever. After being single for hundreds of years, he finally gets a girlfriend. The bad news is that she seems to be investigating and getting close to him so she can kill his two secret identities. Before Reiga can figure out what to do, one of his girlfriend's secret identities suddenly fakes her own death. 《Insider Reveals: On the Day of the Oscar-Winning Actress's Funeral, Her Boyfriend Meets Her Daughter in an Intimate Atmosphere. Actress's Friend Catches Them and Beats the Heartless Scumbag!》 As the headline explodes across the internet, Reiga discovers that he's become a “heartless scumbag.” “?” But his Oscar-winning actress girlfriend and her daughter are the same person! They're all secret identities! Reiga goes online and comes across furious comments from her fans. “Can't that scumbag die with our girl?!” A friend tries to comfort Reiga. “Don't read the hate.” Reiga excitedly replies, “You think I'm worthy of dying and being buried with her? Isn't that an endorsement? Thank you, everyone!” Friend/fans: ??? I met her one evening, when the sunset blazed across the horizon. At that hour, when demons roam, I met the witch who would fill my whole life. Blurb screenshot saved (2026.07.17) Author's Weibo: @JianyunGugu-Jinjiang Reading guide: 1. Updated daily at 6 p.m. If I can't update, I'll post a leave notice. 2. Under Jinjiang's classification rules, this is categorized as no-CP+. There will be a few characters who have feelings for the protagonist. There are familial, platonic, and romantic feelings, and the romantic interests include both male and female characters. The protagonist never reciprocates anyone's feelings, and the story ends with no CP. 3. Although this is a fanfic based on Japanese anime, some changes have been made to the setting for a better reading experience and to accommodate readers who aren't very familiar with Japan. Please remember to distinguish it from reality. If the historical background in the story doesn't match what you know, that's my mistake, but some details can't be changed without affecting the story, so please understand. 4. Please respect one another. Don't mention other authors' works under my story, and don't mention my story under other authors' works. 5. This story is officially serialized on Jinjiang Literature City. All forms of reposting are prohibited. The Jinjiang app costs just three fen per thousand characters, so it's very affordable. Thank you to everyone who supports the official version! Theme: Do your best and have a clear conscience