The Vassal module for Sekigahara: The Unification of Japan has been updated with a fix to an issue that compromised hidden information. Download from the module page here.
Until now, it has been possible to track the subsequent movement of a revealed block after it is re-hidden. From this release, when the final revealed block in a stack is re-hidden, the stack is randomly re-ordered.
Thanks to @Windopaene for bringing this issue to my attention, I hope that this update is a sufficient solution.
For a full overview of the version 1.5 module features, please see “Help using this module” from the module’s drop-down Help… menu or this link .
This release is only backward compatible with other v1.5 releases and requires Vassal v3.7.12 or later.