Three consecutive battles with a horde of large insects. In Battle 2, if either the black mantis or white mantis is defeated first, the intensity of the other's attacks will greatly increase, so it would be best to take both down at the same time.
The nozuchi in Battle 3 will use an attack that forces a unit out of battle, but this can be prevented the turn after the nozuchi is starting to inhale by attacking it with an esper.
Since these are insect enemies, having bug killer should prove to be quite effective.