Zutto! SA Off Summer [English], an hentai doujinshi parodying the Sword Art Online series, by Kawase Seiki
Sugu and her brother are at a festival, and her yukata has the expected effect on her brother. The rest is fap materials, drawn rather well, enjoy your meaty summer wincest ^^
Honest warning, though, the dialogues felt bad a number of times, here, for instance: – “Come, here’s my Frankfurt meal.” – “Ooh, you bully! To have me munch on that like that!” ¯\_(°_o)_/¯
Red_Piotrus, Springborn and PureEnergy, from the E-H Cove, are behind this release, thank you!
By the same artist, I also share SAOn&Off SUMMER and SAOff Autumn.
And now, the download & gallery links 
Open the Complete Pictures Gallery
Download the Free Hentai Manga in a Zip file
(27 MB, 22 pictures, English)
Or you can also use the Alternative:
Zip Mirror #1 – or – Zip Mirror #2
As always Kawase Seiki really knows how to deliver some good SAO hentai with Suguha.
That yukata did not stay on long.
Obligatory clarification: Kirito is only Suguha’s FOSTER/ADOPTIVE brother; they’re actually cousins and already know this by the time Suguha is introduced in-story (IIRC Suguha has this revealed to her after Kirito gets stuck in SAO). They still have a quasi-fraternal relationship out of habit, though.