hm. i found something new here.
Apparently if switch 642 is on (no idea what it is yet) a blood-red and black painting of what looks like the red sun will appear on the top floor at the end of the corridoor, and interacting with the new painting will take you to map 489. ( 赤黒, Red black )
the event is finished - but the map isn't finished atall;
They can hopefully be expected to show up in future versions.