A Confidential Secret: My Girlfriend's Horny True Feelings

From DLsite: "My parents aren't home today." That's what Airi told me shortly after we progressed from childhood friends to lovers. I had no idea that the late bloomer Airi would ask me out; It was finally time for the two of us to have our first time together. Calm down, the rehearsal in my head is perfect! But the entire time, Airi was leading the way. On top of all that, I lost my own boxers; a terrible first experience! I look lame. Huh? Come to think of it, she didn't seem to be in any pain at all when I inserted it; she seemed strangely skilled at it. Could she be cheating? But there's no way that's possible with Airi, of all people. She has a secret she wouldn't tell anyone. "Love me a lot." It's "confidential." Make it a "secret" that you can't tell anyone.