At the world map location prior to the chapter, if both Vega and Shigen are in Holmes’ party and Krishna survived the previous chapter, an event will play where Krishna requests that Shigen kill Vega for her. If you accept and deploy all three on this chapter, another event will play, which improves their supports with each other, but reduces Vega and Shigen to 1 HP. This event is required if you want to access the Krishna duplication glitch later in the game.
As for the chapter itself, the enemies are extremely weak generics that should pose no major threat. Make sure that if Plum was kidnapped, have Holmes or Bartz visit the L-shaped house to have her rejoin with the Dance skill.
After the chapter, the village elder will take you to the treasury to pick five chests out of the 28 chests. It's up to you what you want, and there is plenty to choose from.