Like all FromSoftware games, Armored Core 6 is full of secrets hidden in hard to reach places. Some of the best parts in AC6, including weapons, are hidden away, and they can give you the edge you need in battle. If you want to know where to find all the secret parts in AC6, look no further than this guide.
Armored Core 6 Hidden Parts Locations, All 20 Hidden Chests, Weapons & Items
Only chapters two, three, and four have secrets in Armored Core 6. The important thing is that you complete the mission after collecting secret parts, otherwise they won't be added to your parts list. So make sure you bring a capable build.
Here are all the missions in AC6 with secret parts to collect:
Yes, you read that right. To get the hidden Coral parts from the Chapter Five mission, you need to reach Chapter Five in New Game++. That's the only way to access the "Regain Control of the Xylem" mission.