Honkai: Star Rail: My Sister Herta Turned into an Idiot, So I Have to Spoil Her

[Honkai: Star Rail + fan fiction + multiple heroines + Genshin Impact + System + doting on his little sister + lighthearted comedy] After transmigrating into Honkai: Star Rail, he becomes the genius Herta's... older brother? Baita thought he'd gotten a dream start, but soon discovers this world has gone mad! The aloof Herta has turned into a world-class airhead who can only count on her fingers, and even needs her brother to fasten her buttons; The wealthy Asta has become a miser of the highest order, chasing him down three whole streets over five yuan; Kafka of the Stellaron Hunters is an extreme social recluse who drops to her knees and apologizes in terror if anyone even looks at her; Even Ganyu, just passing by, is a lazy mutt lying on the ground and pretending to be dead! Faced with this bunch of “good-for-nothings” who have nothing going for them but their looks, Baita awakens the **[All-Purpose Big Brother System]**. “Looks like it's up to the only normal person here to save the world.” And so, the whole tone of things suddenly changes: The Doomsday Beast is right on top of them? Baita holds his little sister in one arm and smacks it flying with the other: “Quiet, I'm feeding my little sister!” An Aeon descends? Baita points ahead: “Sis, that glowing hunk looks like a potato chip. Go bite it!” Herta: “Nom! Big brother is the best!”