Krystal comes from the planet Cerinia, and is the sole survivor. In all reality, Krystal is basically a blue fox designed to be the female counterpart of Fox McCloud. This brings the genre of romance to the game, which has received somewhat mixed reviews. Her looks and somewhat "revealing clothing" point to her being the "eye candy" of the game, if such a thing can be said of a video game character.
Despite now being a reoccurring character, she was originally designed to be the protagonist of a game named Dinosaur Planet which was canceled before release. Instead, elements of the game were extracted and put into Star Fox Adventures. Originally designed to look like a 16 year old feline under the guidance of a wizard, she was given three years more of life and turned into a vixen to fit in. In the English voiced versions, she is portrayed to have an Estuary accent.
Her appearance also goes through changes each game.
 Star Fox Adventures
Her story begins in the search for the reasons behind her planet's destruction. At the same time, she's also questioning into the mysterious deaths of her parents. During this search, she comes across a distress signal beaming out from Sauria. She ends up trying to save the planet through the collection of Krazoa Spirits, but is assaulted by an unknown being and ends up trapped within a floating crystal. By the end of the game, Krystal becomes a member of the Star Fox Team.
In Adventures, Krystal wears a somewhat "primitive" set of garments. This includes a yellow haltertop that only covered the chest and a loincloth with slits over the hips, leaving her midriffs and belly button uncovered. Along with those, she also wears sandals, bronze armour-plates on her shoulders, forearms and shins.
Additionally, she also wields a staff which in this game is the primary hand-weapon of Fox McCloud.
 Star Fox Assault
The game Star Fox Assault sees Krystal replacing Peppy on the Star Fox Team as a full fledged member. It is in this game Krystal meets Panther Caroso who attempts to flirt with her, but is not interested due to her love interest with Fox. Her home world comes under attack during the story mode as she finds out through a distress signal sent saying that they're under attack by the Aparoids. It is here they meet up again with Prince Tricky who suggests, after the battle, that Fox should bring Krystal back for a honeymoon one day.
To suit her new role, her attire has drastically changed. Krystal now sports a tight-fitting blue jumpsuit with a black trim. This is along with knee-high blue boots, a tiara, silver rings on her tail, and a silver belt.
 Star Fox Command
Krystal's role in the game varied depending on the player's course. Krystal either joins the Star Wolf Team, the Cornerian Army, goes off on her own or returns to the Star Fox Team. She is no longer in a relationship with Fox, for she broke up with him after he asked her to leave the team for her safety.
In this game, Krystal sports a number of different looks depending on what path the game takes. She is also unique in the fact that she pilots two different ships depending on her allegiance.
Star Fox Team Member
This time the jumpsuit is pink and purple. Along with this she wears a necklace, the tiara again, a communications headset, with a white belt and knee-high boots. Here she pilots the Cloud Runner with twin laser, single lock-on, 1 bomb and good shields and boost.
Cornerian Pilot/Star Wolf Member
This time it's a white jumpsuit with black trim, a yellow scarf, a purple helmet with pink trimming + a yellow C + a cyan visor. Her ship here is a simple Cornerian Fighter, which is the same one used by Bill. Twin lasers, no lock, 2 bombs and good shields and boost.
A much more basic outfit to the others. It consists of a pink shirt with white trim on the collar along with a gold circle around her head charm.
In this version Krystal reverts back to her more primitive style of clothing. She again models the gold bikini top, the bronze armour plates on her wrists, a bracelet on the left wrist, a choker, three-quarter brown pants and three diamond head charms.
 Super Smash Bros. Brawl
Krystal wears the same outfit as she does in Star Fox: Assault for this game.