Talk:Submarine 53cm Bow Torpedo Mount (8 tubes)/@comment-36.81.62.73-20140606102957/@comment-24332640-20140606113054

They don't usually announce ranking reward equipment in these updates, do they?

It seems that the other super cool piece of equipment (the Tomonaga Squadron Tenzan) is from quests so I'm guessing this is a quest thing too. Specifically there's the new quest:

「潜水母艦」と複数の潜水艦（4隻以上）からなら潜水艦隊「第六艦隊」を編成せよ！

This quest requires Taigei--which not many people have at this point--so it's going to take time to confirm this theory. And there might be a follow-up quest that unlocks after the simple fleet compilation one. But that's my bet.