Valkyria Chronicles 3
The Treacherous Valkyria:
Fight versus Riela
Year 1935
Mission: "Valkyria Aboard the Warship"
Objective: Defeat the Valkyria.
Difficulty: ★★★★★
Weapon received: Eberouge (sword)

Finally, the awaited last battle.
I remember seeing this image when the game was in development:
http://sonohara.donmai.us/data/c6d777f2277c63e75e884b415780b322.jpg
I thought by the time that Riela was the final boss of this game. Imagine my surprise and a bit of disappointment when at the end there was that rocket thingy. Luckily, now we get to see her wearing that babydoll and wreaking havoc through this DLC.