Becoming a Trap

A scientist has discovered that our reality is only a secondary universe, and has developed a machine which will cause a subject's mind to switch places with that of another version of themselves in the main universe. As her son Austyn is estimated to have 100% compatibility with the main universe, he is chosen to try the machine.

The experiment goes well, and he wakes up in the main universe, where four genders exist: men, women, futanari, and femboys. Due to his short stature, small penis, and feminine hips, the main universe's Austyn has just been legally designated as a femboy, and so Austyn now needs to adapt to living as one.