[SFM] After Midnight - new SFM futanari work by new author Captain Ameba. Hentai released in 2020.

One summer my aunt invited me to spend time with her and my cousin at their house. She was incredibly happy to see me after a very long time. During this time I got stronger and matured, and she became even more beautiful and sexy. We chatted a little with them and I went to sleep. However, the nocturnal need woke me up and I decided to go pee immediately. On the way I caught my cousin masturbating and to my surprise I discovered she had a male genital organ. That's how I learned their family's secret...