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.
History
The Originally planned beginning and it's long delay
Back in 2013 following the Spring 2013 Event, the planned Friend Fleet system was announced of C2 Kikan's Twitter account (This twitter account served as the former Kancolle Twitter account until the official KanColle Twitter was fully established.) where they announced that they would try to get the Friend Fleet System implemented by the Summer.
However, by the Summer 2013 Event, the devs announced on the C2 Kikan twitter that the plans for the release of the Friend Fleet would be delayed until sometime following the event. But it was around at that time, that KanColle experience a huge popularity boom that resulted in the game surging in popularity and the devs facing a tough situation....
Dealing with the huge amount of players wanting to come in and join.
When the server became flooded, thier plans to release the Friend Fleet System was put on hold and they put thier priority on establishing Servers and controlling player intake via Lottery until things could stable out enough for them to return to work on the Friend Fleet System.
However, this would not be done for several years resulting in nothing being heard of regarding the mechanic until the KanColle Naval Review.
During the KanColle Naval Review in one particular segment of the show. A large gathering of Seiyuus gathered up on the stage floor, all holding scrips in hand. The lights dimmed on the stage as a screen came down and being to display a film of a bunch of girls in cosplay as Kanmusu.
In this skit, the Seiyuus provided the voices of the Kanmusus as the film played out. The summary of the plot focused on a batch of ship girls fighting off against the Abyssal Fleet in Tokyo (at the Tokyo Big Sight area). They however were facing off against a batch of powerful Abyssal Fleet Himes that they were having difficulty trying to defeat. All seemed hopeless until they decided to enter into night battle which then as the screen faded to black the following option appeared on screen:
Do you wish to send in a Friend Fleet Support into Battle?
Yes / No
The Yes option was selected and soon several foreign Kanmusu appeared on screen as they helped aid the other KanMusu until the Abyssal Fleet ran off from the battle.
The Kanmusu celebrated thier victory and then at the end of the play segment, the following word appeared on the screen.
"Friend Fleet System" will be coming soon in 2018.
At the end of the KanColle Naval Review, they showed one more text announcing that the Friend Fleet System would be coming along with Phase 2 at the 5th Anniversary of KanColle.
Current Expectations
Currently, there is not much that can be determined based on the current known details. If the video acting segment at the KanColle Naval Review holds any value, we can expect the Friend Fleet System to act as another line of support for your fleet to aid your fleet in battle to help you gain an advantage over the enemy fleet.
However, because an acting movie segment can only tell so much, how much that was told through the film and how it'll transition into the game is left to be questioned.
More details are to come once the more info of the Friend Fleet System is revealed.