What's this 'map' for?

[valenrei]

Behind the crate in which Julia was locked in(after that she would help you with seven sea mermaid), there was a paper with strange drawings

several squares with arrows and lines, begin with down-right, up-right, down-left, up-left, middle-left, middle-right.

Is this related to the underground or a way to open the central pipe?

[Makina Icyterror]

Oh it's the burner code for the control room. Free mini boss kill if you trigger it.
2:30:21 https://www.youtube.com/watch?v=Trpl5kjQ7uM

[Reimu Hakurei x3]

Originally posted by Makina Icyterror:

Oh it's the burner code for the control room. Free mini boss kill if you trigger it.
2:30:21 https://www.youtube.com/watch?v=Trpl5kjQ7uM

I never knew this, awesome. lol