Friend Fleet
The Friend Fleet system is a system mechanic which has been left in KanColle as a greyed out placeholder in the menu section since 2013. Originally planned to be released during the Late Summer of 2013, this mechanic was intended to engage players to use others players fleets, but due to the popularity boom of KanColle, this mechanic would be postponed for a very long time and would remain inactive.
It wasn't until the Fall of 2017 during the KanColle Naval Review when during the show they would make a big annoucement that the long awaited "Friend Fleet" System would finally be making it's long awaited entrance upon entering Phase 2 of KanColle which is scheduled to being sometime following April 23rd, 2018
As of current, exact details of the Friend Fleet System are only vauge with only the info from the KanColle Naval Review showing a vague concept on how the mechanic will work in the game.