Sixteen Shoukougun

Ibuki is a first-year high school girl who is as strong as any boy. She is always together with Mei, a beautiful and frail girl, and people nicknamed them the prince and princess. She is determined to protect Mei, who has a phobia of men resulting from a kidnapping incident from her elementary school days. But the boy Asada seems determined to seduce Mei as if it were a game... (Source: Margaret Comics, translated)