The missions section shows you all of the missions given to you by the Mama Tamarin. Here you can see what missions you have completed and which missions are yet to be completed. You can also switch to a particular mission in this section if you want to complete them in a particular order. Missions are unlocked when you reach a Journal score of 550. Please note that switching missions will cost Gemberries and the cost is displayed when skipping/choosing a new mission.