Special Stages · Stage 4
Aku Studies 401: Inquiry
悪魔研究Ⅳ考察
Aku Studies 401: Inquiry is a Battle Cats stage in Empress' Report 4. It costs 100 energy and sends 12 enemy spawn lines — led by Cala Maria as the boss — against a 900,000 HP enemy base, and clearing it rewards 8,930 XP. Its enemies carry the Angel and Aku traits, so cats that target them do the most work here.
Data updated: 2026-08-31
100Energy Cost
8,930XP Reward
900,000Enemy Base HP
4,600Stage Length
10Max Enemies
9.5Difficulty
Enemy spawns (12)
| Enemy | Strength | Count | First Spawn | Respawn | Base HP Trigger | Notes |
|---|---|---|---|---|---|---|
 Gabriel | 400% | ∞ | 6.7s | 16.7s~23.3s | 100% | — |
 Miz Devil | 300% | 3 | 10s | 13.3s~16.7s | 100% | — |
 Celeboodle | 800% | 1 | 23.3s | — | 100% | — |
| Gabriel | 400% | 2 | 36.7s | 13.3s~16.7s | 100% | — |
 Aku Gory | 250% | 1 | 46.7s | — | 100% | — |
 H. Nah | 300% | 1 | 0.1s | — | 99% | — |
| Celeboodle | 800% | 4 | 0.1s | 26.7s~30s | 99% | — |
| Aku Gory | 250% | 3 | 0.1s | 53.3s~56.7s | 99% | — |
| Miz Devil | 300% | 12 | 0.1s | 10s~13.3s | 99% | — |
 Medu-san | 100% | 1 | 0.1s | — | 99% | — |
 Cala Maria | 100% | 1 | 0.1s | — | 99% | Boss |
 Ms. Sign | 100% | ∞ | 900s | 900s | 100% | — |