Get to the Island
After confronting the mercenaries outside the hotel, many plot elements happened. Depending on your performance, equipment, and skill checks, some characters' fates may be variable. You'll wake up in your hotel room, and then you'll be able to speak to your partner to get a full update.
Note that because of storyline reasons, you'll be told not to run. This is only plot-based flavor text and can be ignored. Double-clicking to jog somewhere will not harm you.
Frittte becomes open again if you need to shop for medicine. It's advised to have enough medicine and points on you to cover 5 or 6 points of damage each to Health and Morale. You won't need money much longer, so feel free to spend any réal that you want.
At this point in the story, the harbor is on lockdown. As a result, Measurehead is gone, and a box behind him is now accessible with a couple powerful items.
Consider finishing up any Side Quests you may have. The Determine where the shot came from and Where is the rest of the armor quests will be outstanding until the very end of the game, but the rest must be completed now. If a quest required the harbor, it's locked out permanently.
When you're ready for the final sequences of the game, you'll need to go to the Fishing Village. Approach Lilienne, the woman near the docks, and ask to borrow her boat. She'll warn you not to use too much fuel.
WARNING: This is the final point of no return. Once you cross the sea to the island, you are committing to finishing the game. Be sure you've done everything you need to do before going forward.
Once you're on the island, you're on a linear path. After the boat stops, climb the little hill and head into the structure. Inside is a bed that, if slept in, will trigger a long sequence. This can be done now or in a few minutes.
You'll need to go through the blast door at the northwest side of the structure to proceed, but to do that you'll need to fuel the generator in the center of the room. Go to the lower floor and pass southeast beneath the catwalk. The panel to open the door is there. Ignore it for now and exit through the southeast door. Outside, explore around; climb the little hill there and check out the secondary small structure. Aside from an important plot development, there will be a container with an item called LUM Fuel Canister that you need for the generator.
Return to the main structure. Fuel the generator, then interact with the control panel in the southeast corner of the room to open the blast door. This is your last chance to sleep in the bed.
Go through the blast door to find a person near a fire. Speak to the person to initiate a long conversation. At its conclusion, you'll need to double back all the way to your boat. Interact with it to head back to the mainland at the Fishing Village. After one final conversation, you'll be done and the credits will roll!