The main character. A crude-minded, amoral pilot, who fights mostly for money and fun.
- Action Girl: Being the protagonist and all.
- Brawn Hilda: A rare protagonistic example; she has the build of a Russian strongwoman and a fairly tomboyish face.
- Intimate Marks: Pretty much her entire upper torso has her trademark Intestinal Serpent tattoo on it.
- Known Only by Their Nickname: Her actual name is Jackie, though she dislikes it.
- Knuckle Tattoos: Reading "EAT-> SHIT", no less.
- Nominal Hero: At the start, anyway. Likes fighting and money and doesn't really care who gets in the way.
- One-Letter Name: So it is.
- That Man Is Dead: Her reaction to being called "Jackie."
- Trademark Favorite Food: Instant noodles, to the point that her first appearance in both versions is gleefully slurping the stuff down.
- Transhuman: Due to being a pilot, she has minorly improved strength and stamina over a normal human.
J's personal machine. A Lightning Bruiser that can rip apart any machine that gets within melee range of it.
- Awesome, but Impractical: The Judgment Pilebunker does a ridiculous amount of damage, but it has a range of only a few meters and requires twenty seconds of windup, during which gigantic vulnerable rods slowly crank out from the arms. Because of this, it's basically a Finishing Move.
- Crippling Overspecialization: It may be fast, powerful and almost invincible. But it lacks any kind of ranged weapons and has armor so complicated that it needs separate systems for them. Also due to its build, it disallows the choice of customizing it as well as making it very pricy. In-Universe, this was its downfall marketwise.
- Lightning Bruiser: Her mech of choice, the Dragga, is stated to be extremely strong and tough, but also surprisingly fast for something of its size. Its weakness is that it's so overbuilt that it can't really fit anything else on it.
- Power Fist: The Dragga's main weapons are simply punching people with fists larger than most mechs. If it's feeling up for it, it will use its Pilebunkers to punch people really hard.