This is my conjecture, so take it as rumor, but it seems that GIGAMOUS might have left their label, BadeggBox. Today the band renewed their OHP, and also changed their fanmail address―which is no longer in the BadeggBox office. Furthermore, their image at the BadeggBox OHP is in the section with disbanded groups.
So, again, I can't confirm this, but it seems as GIGAMOUS has become independent. That would also make sense in regards to them releasing a best album without disbanding (yet, lol). Please let me know if I've just failed to notice some official announcement!
GIGAMOUS has also announced two more limited-capacity oneman lives, plus a fan meeting: