You can buy these (as well as their HQ) versions from various moogles during Sunbreeze in case you missed last years Summerfest but still want one. Omina and Onoko are for 10k, Lord's and Lady's for 50k.
Yes, the Onoko and the Omina are the standard versions, the Lord and Lady are the +1 versions that have DEF2 instead of 1, as well as increase goldfish scooping ability. I didn't hold on to any scoops after the event, so I don't know if you could still scoop, but I imagine if you had the scoops you could.
As to whether we will see a return of the summer festival moogle quest, who knows. But the halloween event was similar to the one the previous year, but with more hats and staves to be had. So its fairly possible that we will see a return of the event, possibly with more yukatas, fireworks, ghoulish moogles and goldfish scooping goodness. (not to mention the only time I've ever seen an entire server lag for the shear number of ppl swarming upon the quest moogle)
It was a reward for Summerfest 2004. Not sure if it will be available this summer or not. The male version is Lord's Yukata, and looks fairly similar. Maybe I'll send in a fashion shot of it. :)
I could be wrong, I believe the male equivalent of THIS Yukata is the Onoko Yukata. The Lords' Yukata is the male version of the High Quality Onoko Yukata, which adds an additional defense, and increases your goldfish scooping ability, which was an temporary skill (?) used for the last Summerfest.
Again,I could be wrong, it was a while ago and I just started the game around that time, so I was kinda busy learning about the six main jobs, let alone subjobs, etc and special quests.
Daynamitzu Ifrit Rank 5, all jobs.
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Daynamitzu Sam 53 / War 26 San D'Oria Rank 10 Windy Rank 4 Clothcraft 71.4 + 1 {Artisan}
WHM 61 Blm 31 Mnk 10, Thf 25, Rdm 10, SMN 29, NIN 20, PLD 12, DRK 11, DRG 10, RNG 14. SAM 52 BST 17 BRD 5 WAR 36