My brother bought a new apartment, so I visited to celebrate his move. My sister-in-law welcomed me with a smile. It had been a while since I'd seen her, but she looked stunning in her glasses, and I was reminded all over again how incredibly attractive she was. However, I accidentally discovered her secret. While we were toasting with the sake I'd brought as a gift, my brother pulled out his phone and showed me a video. To my shock, it was footage of my sister-in-law appearing in an adult video before she got married. I now knew her past. She begged me, "Please, don't tell anyone. If he finds out and leaves me, I won't be able to go on living..." But her words fell on deaf ears. My brother, drunk, passed out. Seizing the opportunity, I moved closer to my sister-in-law. I caressed her thighs, grabbed her breasts roughly through her knit sweater, and she braced herself with a pained expression. I told her to stay silent as I stripped her down to her underwear, then pressed against her from behind, groping her breasts while threatening her. When I lightly flicked her nipples with my fingers, she let out a trembling "Ugh..." Her body gradually grew hotter. Every time I touched her, my desire intensified. She spread her legs in a wide M on the sofa as I traced her panties. A faint wet stain began to appear. Watching her like this only fueled my arousal further. "Now take them off," I ordered. Hesitantly, she slid her panties down. In that instant, I kissed her deeply and buried my face in her wet pussy. She stifled her moans, but her body responded uncontrollably. Sliding a finger inside and moving it around, she seemed to cry out, "I'm gonna come!" At that moment, my cock was rock hard. I had her touch it, whispering, "I want you to suck it, sister-in-law." Though hesitant at first, she began sucking my cock. Watching her like that made my lust surge even more. "Come here," I beckoned, pulling her onto the sofa to kiss with tongues intertwined. While pleasuring her pussy, she kept saying "No," but her body betrayed her, twitching with pleasure. Then, holding her close, I made her suck my cock while I continued teasing her. Soon, she cried out, "I'm coming!" and climaxed. Watching her lose control, I felt myself nearing the edge. I laid her on the floor, gazed into her face, and asked, "Sister-in-law, do you like me?" She desperately shook her head, but when I kissed her, she passionately tangled her tongue with mine. At that moment, I shouted, "I can't hold it, aaaaaaah!" and shuddered violently. I shot thick cum all over her glasses, then told her, "I'll come play again soon," before leaving the room. Now that I've got her secret, I'm going to enjoy her a lot more from now on.