Celsius
This last chapter begins with a scene on the deck of the Celsius. Depart from the elevator after the scene and return to the bridge for another cutscene with Shinra and Buddy. Once the scene has ended, watch the Sphere that Leblanc gave you at the end of the last chapter.
View Crimson Record 5. You can do this later on in this chapter if you want to, but you might as well have a look at it now since you have the Sphere in hand.
Talk to Buddy and check the map. You should see that all 15 locations have turned into Hotspots. Don’t worry, though! Some are quick to complete. You can complete a few things on the Celsius before you start any of that.
Cabin
There are now two Chocobos wandering around the cabin. This might make it tough to get some rest, but talk to Barkeep and do it anyway. You can finally view the Chapter 5 scene here that takes place between Barkeep and Brother at the bar counter.
As soon as Yuna awakens from her rest, you should hear the dialogue between Brother and Barkeep down below. Walk towards the railing and listen in on their conversation.
Next, head down to the engine room.
Engine Room
Approach and get as close to the engine at the back wall as you can, and then slowly walk back towards the stairs. Doing so will trigger a scene between Yuna and Buddy about the airship. This triggers two Story Completion Percent triggers.
Buddy tells Yuna all about how they found the Celsius and the source of the “Gullwing” moniker.
Once he’s finished telling his story, open up the four treasure chests again to obtain four 
X-Potions, eight Phoenix Downs, seven Remedies, and four Turbo Ethers.
And now you are done with the tasks aboard the Celsius. Head back up to the bridge, speak with Buddy, and select Zanarkand Ruins as your first Hotspot destination.
Checking the “Celsius Complete” box adds the Story Completion Percent for the automatic scenes in Celsius.