Digimon 2.5 is set 25 years after the events of Adventure 02. It follows the adventures of the children of the original 12 DigiDestined as they battle to save the Digital World and their own from the forces of evil.

Dawn Kamiya, Tai and Sora's daughter, has dreamt about adventures in the Digital World ever since she recieved her very own Digimon, Agumon, on her fifth birthday. Since then, she wished the gates to the Digital World would open and allow her and her friends to venture there.

Dawn's wishes are soon answered when unusual activity starts happening in Odaiba, which can only be connected to the Digital World. A mysterious girl and her Digimon appear in Odaiba and the Digital World and begin to cause havoc.

The children soon learn the importance of friendship and teamwork as they begin their adventures throughout the Digital World and on earth learning new ways of digivolving and new tricks. Trying to stop the mysterious girl from ruining the Digital World, they soon learn she is not the true enemy and their real foe is someone more sinister who keeps himself and his identity hidden.

Whilst trying to keep the Digital World and their own world safe, the DigiDestined must located and find eight Digital Emeralds. The emeralds protect each sector of the Digital World and if fallen into the wrong hands they can deliver disasterous effects.

Their mysterious foe singles out Tai and Dawn from the group, believing they are the strongest and must be destoryed. His intentions are soon made clear when he collects enough emeralds to transform into his full form... Myotismon!

Persumed dead 25 years ago when the original 12 DigiDestined defeated him as MaloMyotismon, everyone is shocked at how he has returned. But he has more sinister plans than he did 25 years ago... and is he really the one behind the whole thing?