The requested vessel with name HOUTOKUMARU and MMSI:431680480 and IMO:0 is temporary not in our database.
Perhaps you mean one of the following ships:

Vessel name IMO MMSI In range Destination Last report
HOUTOKUMARU N/A 431002376 Feb 25, 2018 05:10 UTC
HOUTOKUMARU N/A 431400426 Jan 26, 2018 22:08 UTC
HOUTOKUMARU NO.18 N/A 431008113 Sep 16, 2016 00:12 UTC

Also, you may try to find the vessel in our comprehensive Vessels Database or track this ship on the map.