There are a lot of Octopath Traveler 2 side stories where the answer can seem fairly obvious, but you can’t get to it right away, and “Lighthouse Restoration” is one of them. Clearly, you need to go to another lighthouse to fix the one in Canalbrine. You not only need to unlock the boat, which is an expensive purchase, but also have the right person by your side. Fortunately, if you do have a boat and Partitio, it’s an easy quest to complete.
First, you need to talk to the person in front of the lighthouse in Canalbrine to get the “Lighthouse Restoration” side story in Octopath Traveler 2. After that, you need to add Partitio to your party, hop on your boat from the New Delsta Harbor: Anchorage, and head north. There’s a small island directly above it called, appropriately enough, Lighthouse Island.
Now, if people who aren’t Partitio are in your party, you can see the Island Lighthouse Keeper has an Aelmorite Reflector in his inventory. However, you can’t steal it or mug it with people like Throne or Osvald. Also, if you try to guide this person to the lighthouse keeper in Canalbrine, that won’t complete the quest either. You need to have Partitio buy it for 1,500 leaves. Which is very easy, as the chest on that very island has 12,000 leaves in it.
Once you buy the Aelmorite Reflector, head back to the Canalbrine lighthouse to complete “Lighthouse Restoration” in Octopath Traveler 2. You’ll get 12,000 leaves, a Lighthouse Keeper’s Bandana, and a Tough Nut (L).
Octopath Traveler 2 is available for the Switch, PS4, PS5, and PC. A demo is available.