As of the newest ep of Happiness, Jun is no longer a trap. Thus, the inevitable happens and every guy in the school attempts to rape her. great ep. Jun finally got her deepest wish and I can fap without questioning my sexuality.
I thought he returned to his "original form" at the end of the ep. But I don't understand japanese (for the most part), so I could be mistaken. I don't think so though... Being a trap is what makes Jun unique and so much loved ^_^
If you're refering to the latest game, then you're partially wrong. He only turns into a girl durring the H scene, with the use of magic, in a magical realm, and only if the player chooses to do so. He returns to normal afterwards.