Digimon Frontier was first broadcast in 2002. After being prompted by weird phone messages, five children go to a subway station and take a train to the digital world. When they get there, they meet Bokomon and Neemon, who acts as their guides and tell the children that the digital world is being destroyed. The children must fight Cherubimon and his Legendary Warrior servents in order to save the world.

The biggest difference in this season is "Spirit Evoltion," which enables themselves to digivolve into Legendary warriors, rather than having partners. This special evolution involves using spirit artifacts created by the ten Legendary warriors, they were hidden around the Digital World. When the characters first got to the Digital World, their phones turned into digivices they are called D-Tectors.

Each character gets two spirits each a human spirit and a much stronger beast spirit and some transform into even stronger forms by being able to use their two spirits at once and combining all the teen's spirits together. Another difference with this series to the previous three series is that the characters travel around the digital world via trailroads on a digimon called trailmon.

When the five digidestined arrive in the digital world they are hunted by five other legendary warriors who serve the evil Cherubimon. After they defeat four of the enemy's koji finds out that Duskmon who is the fifth evil Legendary warrior is really his brother koichi. With Takuyas help, Koji is able to free his brother and koichi restores the spirit of darkness to it's true form which is called Loweemon.

 After they defeat Cherubimon, they find out that their true enemy is Lucemon who is an ancient and corrupt angel digimon, the previous ten legendary warriors had sealed him away. The digidestined have to fight his two Royal nights before they scan all the data from the digital world which would allow Lucemon to be free. Despite evrything Lucemon is freed and after absorbing the Royal nights he digivolves into a stronger more powerful form. The digidestined combine their power into a new ultimate warrior called Susanoomon, finally defeating Lucemon to save both the Digital World and the Real World.