Extra Stage

The Extra Stage is a post-game mission unlocked after the player has unlocked the "Return to Ahoge Peninsula" achievement by clearing Arcade Mode with both characters and shot types. The mission revolves around the duo returning to the destroyed stronghold in Ahoge Peninsula to find any other artifacts.

Prior to version 1.3.2, the stage was reportedly unplayable due to a bug that prevented the "Return to Ahoge Peninsula" achievement from unlocking. Drillimation acknowledged this in a blog post and a Steam news thread.

Stage context
The stage begins a week after the events of Stage 8. The duo is forced to traverse the entirety of Ahoge Peninsula after Crown Princess Konata refuses to take the duo there via the Victorian Princess. Once they arrive, they realize somebody was already there and is doing the same operation as the duo. That person is confirmed to be Marie Willow, a person trying to gather information from the stronghold. Refusing to hand over the material to Driller and Kagami, she is challenged to an intense danmaku duel, which Driller and Kagami win. After claiming the material, they return to the Victorian Boutique that night to discuss their findings.

Background
The stage takes place in the entirety of Ahoge Peninsula.

Returning enemies

 * Pacoonba
 * Catamine
 * Sparnet
 * Ember
 * Lemonie
 * Crimsonite Grunt

Opponents

 * Lee Gyu-ri (midboss)
 * Marie Willow (boss)