Trails in the Sky FC Hidden Quests List

Chapter 1:
> Amberl Tower Mystery - you have to visit, explore and complete Amberl Tower before heading to Ravennue Village to investigate the mine.

Chapter 2:
> Black Notebook - find the item Black Notebook inside the pirate's hideout at the end of Chapter 1 and present it to the border guards at the Haken Gate before you leave the region for good.

> Lighthouse Monsters - on your way to Ruan take a sidepath and visit the Lighthouse, talk to the old man there and he'll present you with a mission to exterminate an infestation. Do it before walking into Ruan or it'll be gone for good.

(next three can only be done during your stay at Jenis Royal Academy, just before the school festival begins)

> Decorate the Campus - talk to the janitor in front of the schoolhouse to initiate this quest.

> Clear out the School Building - head to the old school building in the east. You have to exterminate all the spiders to complete this quest.

> Research Material Hunt - Talk to Logic in the Material Archives room inside the clubhouse to start this quest.

Chapter 3:
> Temp Librarian Plus (2) (3) - After completing Temp Librarian, you can continue receiving new quests from the Librarian Constance: you need to find three separate books throughout the region using the clues she gives you as a guide. You have until boarding the airship to Leiston Fortress to complete all three.

> Haulage Vehicle Repair - After completing Haulage Vehicle Search quest, go to Zeiss and talk to Prometheus inside Central Factory Workshop. Head back underground and talk to Rudi inside Kaldia Tunnel and he'll give you the Drive Orbment. Give it to Wong at Tratt Plains Road. Needs to be done before the events in Elmo Village.

> Messenger of Love - Also needs to be done before Elmo Village. Visit Wolf Fort and speak to General Brahm. Take his letter (and an appropriate gift) to Faye in Zeiss to complete the quest. You'll get maximum BP for getting her the Wooly Knit-Hat from Bell Station General Goods as a gift.

Chapter 4:
>The Embassy Mission - not really hidden, but quite missable since it's only available after completing the final dungeon. When given free reign in Grancel: head to the castle and talk to Olivier, then return to the Guild and check the boards for one final mission. Complete and report it before relaxing at the rest stop in the eastern block of town.