Infected Digimon

Infected Digimon (感染デジモン) is the overarching mystery of Digimon Adventure tri. Not much is known about the phenomenon, except it causes the Digimon in question to act out in a berserk manner.

Digimon Adventure tri.
Infected Digimon are a phenomenon that causes Digimon to go berserk. The cause is currently unknown, but humans from the Incorporated Administrative Agency and Digimon in the Digital World are both attempting to solve the crisis and mitigate the damage.

Kuwagamon
Kuwagamon is one of the first Digimon to be shown to be infected. It often appears in the Human World and disrupts electronics. One eventually appears at Taichi "Tai" Kamiya's soccer match, causing Tai to give chase. It eventually attacks him, causing a widespread swathe of destruction. saves Tai, and then proceeds to get into a battle that takes them to Haneda Airport, where they cause further destruction as Kuwagamon gets the upper-hand. The other appear on scene, but two more Kuwagamon emerge. ,, , and take care of the other two, but the first manages to defeat. Before it can land the killing blow, 's hand appears from a portal and drags the Kuwagamon back into it.

Ogremon


Ogremon attacks Primary Village and destroys the as  watches on in horror. He is chased by and attempts to escape to the Real World, where the Incorporated Administrative Agency meets him. Ogremon is too strong, however, and breaks past their defensive line, but he is pulled back by Leomon. Later, Ogremon once again resurfaces in the Real World, and is met by and. Once again, Leomon appears and drags Ogremon back to the Digital World.

Leomon


Leomon ends up dealing with an infection when the Digimon Emperor kidnaps. It paralyzes him during the fight with. The residual traces of the infection appear to linger and seems to be the impetus that causes Meicoomon to kill him.

Imperialdramon Dragon Mode


What appears to be an infected Imperialdramon Dragon Mode is under the control of the Digimon Emperor when he kidnaps. He attacks and, only to be defeated by their newly-attained Mega forms,  and.

Meicoomon


Maki Himekawa reveals that she believes Meicoomon to be the source of the infection.