The Last Story/The Vono Islands

Repairs have begun on the ship's damage, and a few of the mercenaries are interested in spending some time ashore. Speak to Dagran, who is standing at the top of the staircase. He says that Mirania and Yurick both asked him if they can go ashore, but he'll leave the final decision to you. Mirania is located in the room just in front of the ship's stern, and letting her go ashore will take you to the Mysterious Forest. Yurick is located in the room just behind the captain's quarters, and letting him go ashore will take you to the Shipwreck. You can go to them in either order, but you must complete both chapters before progressing.

If you're concerned about difficulty, head to Mysterious Forest first. The enemies you encounter there, including the boss, are slightly easier to deal with. Since you'll be acquiring experience along the way, when you reach Shipwreck you will be better suited to handle the challenges there. Shipwreck is somewhat harder, not because of the enemies, but because the final boss battle involves a surprise.
 * Deciding which to do first