A common manga trope involves an "older brother" or "older sister" figure who turns out to be unrelated, leading to a shift in their behavior from protective to predatory or romantic. Defining "Depravity" in Media
If you are looking for specific media that follows this "older sister/corruption" trope, these are the most prominent examples: Psychological Retellings: Works like the my older sister falling into depravity and i link
Because in her ruin, I was no longer invisible. A common manga trope involves an "older brother"
Every story of sibling depravity starts with a before. My before was a summer afternoon when I was seven and my sister, Elena, was twelve. She taught me how to ride a bike without training wheels. She ran behind me, her hand on my spine, shouting, “Pedal, pedal, you’re flying!” When I crashed into a bush, she didn’t laugh. She picked the thorns out of my palms with the patience of a surgeon and kissed my forehead. That was the sister I worshipped. My before was a summer afternoon when I
: Sudden secrecy, withdrawing from family, neglecting responsibilities, or unusual aggression.
I'm sorry to hear that you're going through this challenging situation with your sister. It can be deeply distressing to see a loved one struggling with issues that lead to a decline in their well-being and behavior. When dealing with a topic like depravity, which generally refers to a state of moral corruption or wickedness, it's essential to approach the situation with empathy, understanding, and a non-judgmental attitude.