Japan's Inside Gaming site has posted packaging shots for Spike Chunsoft's Attack on Titan: The Last Wings of Mankind Nintendo 3DS game. What's notable about their cover picture is that it shows a D:17+ content rating from Computer Entertainment Rating Organization.
The scale includes
|All ages (全年齢対象 Zen nenrei taishō)|
|Ages 12 and up (12才以上対象 Jūnisai ijō taishō)|
|Ages 15 and up (15才以上対象 Jūgosai ijō taishō)|
|Ages 17 and up (17才以上対象 Jūnanasai ijō taishō)|
|Ages 18 and up only (18才以上のみ対象 Jūhassai ijō nomi taishō)|
For reference, the first Akiba's Trip game, where you walk around Akihabara defeating vampire like creature's by pulling off their clothes, got a C:15 rating.