Signed Celadon Kogo & Cover in Marked Tomobako: Translation & Age, Please?

I have a sense this isn't very old, mostly due to its pristine condition an' lack of wear or damage to the box. I'm not familiar with the mark, but hope that one of y'all will be better equipped to ID the maker by it, an' perhaps glean some pertinent meaning from the characters on the box cover. It's 3 1/2" diameter, 1 1/4" high; weight is ~8 1/4 oz plus the box. I've had it ~15 years, bought from a reputable dealer, but can't recall what he said about it, nor what it cost me. Thanks for lookin'!

 

Looks like Korean celadon, beautiful.