The Key

Escanor's group was actually confused when Ace introduced to them the technology.

After all, the Lost Technology is something that couldn't be bought with money... No one knows the origin of this mysterious knowledge and there were only clues that it came from the Northern Continent or the legendary city under the sea...

Aside from this, no one knows where can they find them as they were mostly hidden or destroyed through the passage of time. Some of this incomplete Lost Technology would appear in the black market, auctions, and even in some museums but it is extremely rare to happen...

However, right now, what in front of them is a piece of detailed information about Optical Phenomena Manipulation. A genuine Lost Technology that Ace calls Arcane Technology.

He said that he already learned this knowledge and it was now time for them to study it and help him continue his project...