Thread:Esdeath-sama/@comment-24986573-20161120121136/@comment-24986573-20161120121511

I dug about a bit and this is what i found if it helps.

This might be what your looking for.
 * E-5 has an additional starting location[2]  that can be unlocked by getting at least 2 S Ranks at any combination of the following air raid nodes C, E, D and an S rank at surface combat nodes A on E-5.[3]