A Heroine with Secret Identities? So What!

[Morally gray medical genius younger sister VS taciturn soldier older sister, a beacon of righteousness. They save each other.] [The older sister has a love interest; the younger sister does not.] Bai Cheng: “So, I transmigrated…” She looks through the memories. “A secret-identity story, with the younger sister as the heroine and a villain… A villain? Not a wicked supporting woman, a white lotus or a green tea?” “Wow! This is fun!” … Bai Cheng: “Sister, do you like the little gift I got you?” Bai Lan: “…Boring.” Bai Cheng: “Whether it’s boring or not doesn’t matter, as long as it’s useful.” … “Bai Lan, remember this: I gave you the chance to survive. I didn’t lose it to you…”