After defeating Grimdo during the events of Ultraman Taiga: New Generation Climax, Tri-Squad → Ultraman Taiga, Ultraman Titas & Ultraman Fuma were training themselves at the other side of the galaxy.
That's when 'the one who controls the Zettons' the Space Fear-Demon Zett attacks them with the help of his Zetton Army. Tri-Squad struggles to fight them.
The one who was working behind the scenes was Absolute Tartarus.
Ultraman Zero decides to take countermeasures against him.
Even the new member of Space Guard → Ultraman Z decides to fight against the Absolute Conspiracy with his reliable senior Ultraman Mebius.