The ”application” is the runtime software.
The “user data” directory contains a “state” file with your personal settings choices.
The “state file” contains an “archive” zip file with all of the items on your “shelf”. Two other zip files contain items from your “archive” and “trash” shelves.
Application Location: C:\%USERNAME%\AppData\Local\Hoku User Data: C:\%USERNAME%\AppData\Local\HokuData
Application Location: /Applications/Hoku.app User Data Location: /Users/$USER/Library/Application Support/HokuData
Application Location: /opt/hoku User Data Location: /home/username/.local/share/HokuData
It is better to leave it alone, but if you choose to explore your HokuData directory, please make a copy of the HokuData directory first, so that you can restore it, if necessary.