This (title) is part of the missions interface. You can select 3 missions that are your "Quick Missions" which are easier to get started.

I thought of this because I am getting up my status bomber set, as I am doing RJP for the set being 4 / part 3 star. Every time I have to go back down into RJP, it is a pain to click back a ton through all of the rank missions to find it.

This way, it is less of a hassle.