Montana Jones

Montana (モンタナ・ジョーンズ, Montana Jōnzu) is always seeking the unknown and isn't afraid to do dangerous things. Together with his cousin Alfred he travels around the world finding treasures for Gerrit, Alfred's professor. The group's plans are often foiled by Lord Zero. Montana works in his aunt's restaurant to finance his airplane Ketty, a Supermarine GS waterplane constantly in need of repair. He lives somewhere on the coast in Boston. It is believed that Montana is infatuated with Melissa Thorn.

He was voiced by Akio Ohtsuka.

Alfred (アルフレッド・ジョーンズ, Arufureddo Jōnzu) likes to study old cultures, strange languages, and treasures. On the other hand, he hates danger, travelling, and can't swim, making him an opposite of his cousin Montana. Together, the two make a good team. Alfred loves his mother and eating spaghetti bolognese, which he often prepares for Melissa and Montana.

He was voiced by Ryusei Nakao.

Melissa Thorn (メリッサ・ソーン, Merissa Sōn) often helps Montana and Alfred and is the daughter of a diplomat. Melissa is a journalist and enjoys shopping and adventures with the two. In the last episode her father is revealed to be Professor Gerrit, explaining why Melissa was always at the right time and place to help Montana and Alfred.

She was voiced by Junko Iwao.

Agatha (アガサ・ジョーンズ, Agasa Jōnzu)（episodes 1-8, 10, 12-13, 15-18, 23, 24-28, 33-34, 38-39, 45, 51-52) is Alfred's mother, and Montana's aunt.

She was voiced by Rihoko Yoshida.

Lord Zero (ゼロ卿, Zero-kyō) is the main antagonist of the story, constantly trying to get all the treasure for himself only to be thwarted by Montana and Alfred. Usually his plans are foiled because of a mistake from his minions Slim, Slam or Dr. Nitro. Lord Zero is notable for his walking staffs, which all have strange and diverse functionalities. Zero is constantly in a bad mood, and personally hates the excuse "I'm sorry, it wouldn't have happened if you gave me more time and money."

He was voiced by Ryuzaburo Otomo.

Slim and Slam (スリム＆スラム, Surimu to Suramu) are the bumbling minions of Lord Zero. The two know searching for the treasures themselves would be more successful but their loyalty is greater than their daring. They often do the difficult work for Lord Zero, and when things go wrong they usually take the blame. Ironically, Slim is the larger of the two.

Slim was voiced by Toshiharu Sakurai and Slam was voiced by Chō.

Doctor Nitro (ニトロ博士, Nitoro-hakase) is a minion of Lord Zero and a genius. He is a creator of machines for Lord Zero that never seem to work the right way, and often gives the excuse "it wouldn't have happened if you gave me more time and money" to defend them. Unfortunately, Lord Zero hates that excuse.

He was voiced by Junpei Takiguchi.