Not sure if this have been suggested before, so I'm just gonna bring it up.
As you know, the mini-map on the top right can be minimised. The events list on the left can be minimised. However, the missions list on the right cannot. It would be nice if that list can be minimised as well, especially once you've done all the missions for the day or week, and at level 85, all it shows is to obtain more summons or recruit more ninjas, which really isn't all too useful to look at.
Hopefully, this can be implemented. Not a game changer, but a clutter cleaner. ;P