Hi HellWimp!
Thanks for your question :)
Technically, there is two true endings - one for the male route and one for the female route that are both (in a way) intertwined (and the way the game is designed, you will need to experience the game as both to achieve). Both these endings will result in the same true ending achievements and credit unlocks regardless of whether you are a boy or girl.
Because the true routes almost need each other, I would argue that neither male or female route is default as the game was created from day one to encompass both in meaningful ways :)
I hope this helps!
<3 MoltenCherry
P.S - an update is coming soon that will add a small amount of content to all romantic endings and true endings! :D So hopefully, they will be even better!