Better Summary:
If Goku didn't know better than he'd say that his Grandfather's hut had gained a brand new hole behind it. When he'd first seen it, Goku's Grandpa Gohan had described the hole as a Window or even a Mirror. As for the girl who showed up on the other side... she was from a mirror dimension. A flipped world. A world exactly like their own but different.
OR
Basically, what type of havoc would ensue on canon if a female Harry Potter (Harrietta Potter) and Son Goku started out as childhood friends? This is my take on it.
*clears throat*
Hey guys! If you like the idea of meshing Dragonball and Harry Potter worlds together and decide to write your own fanfic about it- please do not copy this work! But I'd certainly love to read your story though, I feel like there aren't that many out there.
This story is not suitable for children or teens below the age of 16! It has non-explicit references to abuse and/or child endangerment/violence, some general violence, and the descriptions of injuries resulting of such things- so there will be gore. There are mentions of abuse, typical Dragonball and Harry Potter violence, mentions of blood, realistic descriptions of wounds and/or effects of magic gone wrong, etc.
Which is why I've decided to rate this story as Mature (M).
If you're okay with that- then great! Please proceed!
(This was my warning, by the way. I won't bother with another.)