T r a n s l a t i o n s ;
REN-GETSU
Getsu stands for moon or month (I won't say this again, 'kay?) and ren stands for pair, link or together. So Ren-getsu would be "paired moon" or "linked moon".

GEN-GETSU
Gen stands for illusion or phantom. Thus, Gen-getsu would be "phantom moon" or "moon of illusion".

HI-GETSU
Hi in this case means "fly". So Hi-getsu would translate to "flying moon".

SHI-GETSU
Shi in this case stands for purple/violet, so Shi-getsu is "purple moon". Hm?

FUKU-GETSU
Fuku in this case would be "lie down" or prostrate. Prostrate moon... Heh, poor Mugee.

KA-GETSU
Ka translates to flower, glorious or brilliant. So Ka-getsu would be...flower-moon? Okay.

RAN-GETSU
Ran stands for storm, so Ran-getsu would be "storming moon" or something of the like.