|Appears In||Anime and Manga|
|Debut (Anime)||Episode 3|
|Family||Jake (father); deceased|
|Seiyū (Japanese)||Daisuke Sakaguchi|
|Voice actor(s) (English)||Bryce Papenbrook|
Despite being the weakest and the one with the least experience on Team MÄR, he is the most resolute. Whenever he is offered the chance to grow stronger he eagerly accepts it even knowing the hardships that he will endure. He also has a tendency to develop hopeless crushes on cute girls, opponents or otherwise.
Jack is the son of Jake, a member of the Cross Guard and his wife who helps out around the farm. Jack used to live with his mother and father, but his father left to go fight in the 1st War against the Chess Pieces. Jake was killed by the Chess Piece Weasel in the War Games. Later a messenger came by their house and told them of Jake's death. He also gave him his dad's Arm, the Battle Shovel, which he fought with in the war. Afterwords Jack would live alone with his mother and help grow the crops.
Sometime later Jack's farm would come under attack from the vegetarian Rogelu Brothers, and he would try to stop them only to be faced with failure. Only until he meets Ginta, who inspires and assists him, does he defeat the werewolves.
Jack meets Ginta Toramizu early in his adventure when he and Babbo stumble upon his garden. After Ginta helps him beat the Rogelu Brothers, he and Ginta become best friends and he joins Ginta and Babbo on their journey.
After a battle with Stanley of Luberia and an encounter with Alviss, Jack helps Ginta and Edward the Dog into preventing the Chess Piece Rooks Ian and Loco from trying to claim Snow for the Chess Piece Queen Diana. During this time, Edward told Jack to hit him on the head with his Battle Scoop which helped into turning Edward into Alan. When the Knight Halloween came to recall Ian and Loco to Lestava Castle, Jack unwittingly blurted out that Ginta was from Earth.
To train for the upcoming battle with The Chess Pieces, Jack was paired up with Dorothy in the Training Gate. After the training, Jack helped the others fend of Ian and the Pawn Gido.
In the preliminaries of The War Games, he managed to defeat a Pawn.
In the 1st Round of the War Games where he fought alongside Ginta and Alviss, Jack fought against the Rook Pano Rodokin and ended up losing when her Ball Hammer hit his crotch.
During the 2nd Round of the War Games, he and Ginta were in Gaira's Training Gate.
Jack fought Pano again in the 3rd Round, and used the Magic Mushrooms to cause Pano to see illusions, thus granting him victory.
In the 4th Round of the War Games, he fought the Bishop Kollekio at Iceberg Field where his Earth Beans couldn't grow. But when shrunken by Kollekio's Magic Hammer, Jack managed to make them grow within Kollekio winning Jack the match.
When in Caldia, Jack received two Guardian ÄRMs.
In the 5th Round of the War Games, he fought the Knight Candice and was almost turned to stone by her Gorgon until he used his Guardian ÄRM Mehitos to destroy it. The match ended in a draw.
During the 6th Round, Jack was training in Gaira's Training Gate to become stronger.
When Team MÄR ended up in Tokyo, Jack ended up with a Pierce on his forehead which gave him the memory of a leader of a gang from the school that rivals Ginta's school. Ginta managed to fight Jack and get the Pierce off him.
Jack finally encountered Weasel in the Final Round of the War Games, where Jack reminded Weasel of Jake because they used similar ÄRM. During the battle, Jack managed to burn the tree on Weasel's head using his Guardian ÄRM Kikazoku Fire . Jack won the match, avenging his father's death, and Weasel stated that Jack had surpassed his father.
Jack participated in storming Lestava Castle to rescue Snow from Diana. He, alongside Team MÄR, ended up captured by the Ghost Chess, but escaped. When the Chess Piece King Caldia's Orb (in the form of Danna Toramizu in knight armor) showed up in person, Jack comforted Pano when Leno and Garon were killed by him. Jack was among the Team MÄR members who weren't killed by him. After Caldia's Orb was destroyed, Jack managed to perfect his Earth Beans to grow to the sky.
A user of plant/earth-type ÄRMs:
- Battle Shovel: Also called the Earth Scoop, a Weapon ÄRM that Jack's Dad left for him that can also be used as a weapon. The ÄRM's typically horrendously weak, it is afterward upgraded by Dorothy with magic stones.
- Mehitos: From beneath the ground, this cephalotus Guardian bursts forth to Jack's summon and, under his commands, consumes all adversaries.
- Kikazoku Fire: Using a ruby-engraved ring Guardian ÄRM as a medium, Jack calls to his side a flame-haired cheery midget donning Arabian clothes with "at your service" manners and when the order for destruction is issued, it will practially reduce everything to ashes with its flame. He likely has his own will.
- Earth Wave: Using the power of the magic stones, Jack's Battle Shovel sends out a small earthquake towards his opponent.
- Earth Beans: Jack scatters several small beans on the ground and uses his Battle Shovel to make them instantly grow into giant vines to snare his enemies.
- Magic Mushrooms: Jack spreads spores onto his enemy that quickly sprout into mushrooms. These mushrooms then emit hallucinogens into his enemy, causing them to see illusions.
- Bean Shield: Jack uses his Battle Shovel to instantly grow a giant, hollow bean that he can then hide inside to avoid attacks.
- Jack resembles the character Jack from the popular fairy tale Jack and the Beanstalk. He lives on a farm, eventually grows a huge beanstalk up into the clouds, has magic beans, and in the fight against Kollekio , he is shrunk and thus fights a 'giant'.
- Jack is commonly referred to as a monkey due to his appearance, mannerisms, and his tendency to climb tall steep surfaces. The climbing aspect could be a trait shared with his fairy tale origins as Jack climbed the beanstalk to see what was in the clouds.