Please note that there are spoilers that you may want to avoid. After beating all Chapter four bosses, there is one more task you can perform to reach endgame content, and it is the final sidequest known as "At Journey's End". Some need to be completed first, however. As soon as you have finished "Alphas and Impresario's Request" a fast travel spot on the map will appear (near Everhold), allowing you the access to Ruins of Hornburg and its final dungeon, Gate of Finis. Before stepping in, note that it is important to level up your unused characters too since for the first time you will be using both parties for the final stage. A well set strategy is recommended as well.

Unlockable	How to unlock
"Alphas and the Impresario"	As soon as all previous sidequests are completed, fast travel to S'waarki, head to the west and you will find Impresario and Alpha. Beat the miniboss.
"Daughter of Dark God (I)"	Duel/Provoke Alphas, a guard that can be found in the outside of Ravus Manor in Bolderfall.
"Daughter of Dark God (II)"	Alphas will follow Lyblac to Saintsbridge. Scrutinize/Inquire to get his poem, and bring it to Flora, who is at the cathedral entrance.
"In Search of Father (I)"	Guide/Allure "Aspiring Actor" (a NPC which can be found at the east side of Noblecourt) to Kit, who is in Noblecourt too.
"In Search of Father (II)"	Kit is located in Moonstruck Coast. Give him the Lapis Lazuli, which can be Purchased/Stolen from a merchant on Grandport.
"Kit, The Traveler"	Give him a Healing Grape after beating 1st Chapter on any character (you will find him outside your starting area)