Cave Secret

Chantelise
Terran Ruins
Cave
I had to replay the game up to where I recorded to continue the video series, and naturally I got stuck right at the crab battle where I was last time. I level grind to address the problem, and as I do I go back over the levels to unlock the secrets I missed.
This one stumped me for a while, so I went to the internet, and then I felt dumb.