I'm the Top-Tier Star's Older Sister

[Main story complete] When Si Xia was little, her parents divorced and each remarried. Afraid she might be mistreated, her grandfather took her in and raised her. After graduating from college, she returned from overseas, and a family variety show called My Little Brother approached her. It turned out that her two younger brothers, born from her parents' second marriages, had both entered show business and become hugely popular top stars. The production team wanted her on the show to showcase their family life and keep her brothers on track with their studies and growth. Si Xia took one look at her brothers' grades. Her younger paternal half-brother, Si Ye, was the boy band's dance ace. His dancing was cool, powerful, and captivating. His math score was 31. Her younger maternal half-brother, Xue Yang, was the boy band's lead vocalist. His voice was clear and lovely, like a gift from heaven. His English score was 28. Si Xia: ...Where did these illiterates come from? Is it too late to disown them? Si Ye and Xue Yang had known since childhood that they had an older sister, but she lived overseas and they rarely saw her, so they didn't know her well. That was until she returned to the country and appeared on the same variety show as them. They resisted again and again, and failed again and again, subdued by the female demon and forced to study through tears. Si Ye & Xue Yang: What kind of monster is she? Can we ask her to disown us already?! Si Xia: Oh? Are you sure? Then they saw the new guests Si Xia had invited appear on the show one after another A mixed-race young star who'd become an international singing sensation called her Big Sis affectionately, A rising young film director called her Big Sis like an old friend, A top bestselling novelist shyly called her Big Sis, A genius young PhD in physics lazily called her Big Sis... Si Ye & Xue Yang: … Damn. Si Xia, how many good little brothers do you have, exactly? You damn men, quit pretending! Get lost! Stay away from my sister! [Blurb written on 2021/10/10] The entertainment industry elements in this story are based on gossip I've seen and the needs of the plot. The author doesn't follow celebrities. There are no real-life models. Please don't associate the characters with real people. One-on-one romance, no competing for the male lead. The male lead has already been chosen. [Check out my completed novel: Sneaking into My Master's Abode Every Night] Nan Xu transmigrated into a xianxia romance novel and became the child of a dragon vein, the divine beast Suanni. The heroine in the book was a disciple of the immortals, caught in a melodramatic entanglement with the male lead, the Demon Lord. And she, the vicious supporting character, was the Demon Lord's devoted simp. For the Demon Lord, she infiltrated the immortal sect and became the heroine's junior sister. Their master happened to be the frail, unforgettable love the heroine couldn't get over: Sword Immortal Li Yun. The Demon Lord told her to become his disciple, train hard, and earn Li Yun's trust so he could use the opportunity to kill his rival. The transmigrated Nan Xu: ... She wasn't going to keep being a simp. She'd just go through the motions. If the Demon Lord asked, she'd tell him she wasn't close to Li Yun. From then on, she dozed off in her master's lessons and slacked off while her senior sister practiced swordsmanship. She coasted through secret-realm training and skipped sect assignments. Life was so much better when she could lie flat. The only trouble was that, as a fire-type divine beast, she couldn't suppress the true fire inside her every night and would turn into a fluffy ball. Troubled, Nan Xu secretly found a place to enjoy some air-conditioning: Sword Immortal Li Yun's abode. This frail master had bone-deep cold energy, which she could eat like popsicles to suppress the true fire inside her. And Li Yun seemed to think she was just a little cat that had wandered into his abode, so he let her come and go as she pleased. She stayed in his abode at night, then slipped away at dawn, returning to her usual role as the junior sister everyone thought was utterly unremarkable and always slacking off. Everything was perfect. Until one day, in a secret realm, she took a nap. When she opened her eyes, she saw a man's dark hair hanging beside her cheek and his handsome, aloof profile. Beside them, her senior sister looked on the verge of tears. "Junior Sister, why are you lying in Master's arms?" The Demon Lord's eyes reddened. "A Xu, is this what you meant when you said you weren't close?" Nan Xu: ... This was bad. Her air-conditioning scheme had backfired. Sword Immortal Li Yun was a peerless genius, famous throughout the land and the most outstanding cultivator of his generation. But he was gravely injured in a war between immortals and demons. The cold energy had penetrated his bones, leaving him unable to cultivate and practically useless. To keep him from getting bored, the sect took on one disciple after another for him. He occasionally taught them, but spent most of his time in seclusion, out of sight. His disciples were restless too, all looking to climb the ladder elsewhere. His days were dull, and he could no longer muster the slightest interest in the mortal world. Until one day, he met a slow-witted, carefree little disciple. And a little cat that snuck into his abode late at night. Aloof, reclusive master x slacking-off fluffy-ball disciple Theme: Study hard and improve every day