At first, she seemed like a very pure and gentle older sister type. She's been living next door to me since last month. Our interactions were limited, usually just brief small talk when taking out the trash in the morning. Apparently, she works as a tutor. From her kind and calm demeanor, I heard she's well-liked by her coworkers and students alike. She's been living with her boyfriend since last week, and he also seemed like a nice guy. Occasionally, when walking near the apartment, I'd see them out on cute, loving dates. Those moments always made me smile. However, when her boyfriend went on a business trip for two or three days, I discovered she was alone in her room one night. It was slightly muggy, so her window was slightly open—and from it, I heard lewd moaning. Curious, I peeked inside and saw her completely naked, doing something with a man. From her passionate moans, it was clear she was taking the lead, moving intensely. I don't know when that man left, but the next morning, I ran into her by the dumpster. She greeted me with her usual gentle smile. They always say appearances can be deceiving—maybe that saying really applies to someone like her.