Ultraman Tiga Gaiden: Revival of The Ancient Giant is set many years after the end of the original Ultraman Tiga series, in which Daigo Madoka (host of Ultraman Tiga) has a son with Rena, named Tsubasa Madoka. Tsubasa is a member of the team featured in Ultraman Dyna, Super GUTS.
In the beginning of this film the narrator explains that 5000 years ago a giant of light protected this particular village from a monster but disappeared after that.
One day while returning from a mission with Super Guts, Tsubasa (the son of Daigo and Rena) is caught in a sudden storm and encounters a monster. Tsubasa tries to contact Super GUTS headquarters, but a wormhole appears and sucks in both of them. The two return to the past, 5000 years ago where Tsubasa crash lands into a mountain, the nearby villagers, one of which is a boy named Amu, rescues Tsubasa, but to their horror, afterwards the same monster that attacked Tsubasa attacks the village.
On the other hand, a wandering monster hunter stumbles upon the legendary Spark Lens beside a monster she just killed, not knowing what it is she keeps it but when she approaches the village under attack the Spark Lens starts to shiver. The village’s wooden defenses are no match for the monster and the village heavily damaged with the defenders of the village trying to confront it with spears.
It turns out the monster was ‘summoned’ to this time by a sorcerer who wanted to prevent the revival of Tiga by destroying the golden pyramid in which his remains lay petrified (The very same one Daigo enters and discovers Ultraman Tiga in Episode One of Ultraman Tiga).
When Tsubasa sees the Spark Lens fall out the monster hunter’s bag he instantly notices it looks the one his father used to transform into Tiga. He takes it away before the monster hunter can object and transforms into Tiga. The monster is defeated easily but at the end Tiga disappears as Tsubasa was not destined to truly wield his power, and the whole village is devastated…