After I Learned the Plot, My Senior Sister's Character Fell Apart

(Transmigrate into a book, sweet romance, empress, one female lead) Lin Chuan transmigrates into a world, only to discover that it’s the very world he created! The Holy Land’s chief disciple, seemingly cold and heartless, is actually a kindhearted tsundere? The bloodthirsty Demon Sect Empress has a mysterious past no one knows about? And the brutal Demon Empress, after taking human form, turns out to be a legally aged loli? Of course, all these are closely guarded secrets. He’s the only one who knows them inside out, since he created this world. From then on, the senior sister’s aloof persona begins to crumble.