Memories about conceptual invasions should normally disappear from people's minds except of but those involved in the defense.
However, people remembered everything, and the name of Kairos seemed to be spreading as a hero of fighting against other worlds.

The explorers visit the Kairos' secret base to learn about "invasion killing" as Kairos had previously promised.
But Kairos was not there, and in his place sat Frank, the grumpy-looking commander of the Duchy of Schlinger.
Yomi said that Kairos went out alone to investigate and has not returned yet...

Where is Kairos?
Is there a way to solve the bad situation in the other world?

Everything depends on the explorers...