Talk:World 1/@comment-24687840-20140315145532/@comment-14.192.210.153-20140315172422

Just saw this over Kancolle Forum:

Quoted from official twitter: 本作戦は【Extra Operation】仕様(※後述)となっています. 本海域はその難易度/ドロップ内容がゲーム進捗によって変化します.

Translation at the forums: The characteristics of this [Extra Operation] are: The difficulty and drops of the maps will be based on you map clearing progress

However, how I read the original post is difficulty (normal/hard mode) and drops will be based on  your "game progression". But not sure if game progression is actually based on the maps you've cleared or HQ lvl... though these two probably goes hand in hand.