Suffering from premature ejaculation and unable to satisfy my wife, I was secretly using a masturbator to train my cock when my sister-in-law, Nana Mi, caught me. I explained the situation, and she offered to help me overcome my condition. From then on, I began a daily routine of sneaking away from my wife to have Nana Mi train my cock with handjob sessions. She enthusiastically helped me, and our sessions escalated quickly with kissing and blowjobs becoming more intense. Eventually, we made a promise—if I could last 15 minutes, I'd be allowed to penetrate her pussy. Will I finally succeed in lasting long enough to enter her? But when we finally join, guilt over cheating overwhelms me... Ahhh—I want to thrust my cock deep into my sister-in-law's pussy and shoot every drop of my cum inside her!