It's "Pineapple Day", almost certainly because of another number pun, although I'm not sure how. (8 = hachi -> ha -> pa, 1 = ichi -> i, 7 = nana -> na, and somehow "puru" comes from somewhere.)

There's also a new batch of "Flat Ushio" images.

https://twitter.com/otoufu_material/status/500854002611781635/photo/1
https://twitter.com/otoufu_material/status/500856129841160194/photo/1
https://twitter.com/otoufu_material/status/500859030286237696/photo/1
https://twitter.com/otoufu_material/status/500894295969513472/photo/1
https://twitter.com/otoufu_material/status/500903366927474690/photo/1
https://twitter.com/otoufu_material/status/500907560111570944/photo/1
https://twitter.com/otoufu_material/status/500932778725105664/photo/1
https://twitter.com/otoufu_material/status/500972305711775744/photo/1
https://twitter.com/otoufu_material/status/500980674283573248/photo/1
https://twitter.com/otoufu_material/status/501005688877744128/photo/1

She appears to be visiting a resort dock... I mean bathhouse!

EDIT: More after Otoufu woke up:
https://twitter.com/otoufu_material/status/501176608796200961/photo/1
https://twitter.com/otoufu_material/status/501202520237035520/photo/1
https://twitter.com/otoufu_material/status/501209851557449728/photo/1
https://twitter.com/otoufu_material/status/501210952142835713/photo/1
https://twitter.com/otoufu_material/status/501212418215653376/photo/1
https://twitter.com/otoufu_material/status/501221782896914432/photo/1
https://twitter.com/otoufu_material/status/501223076638384130/photo/1

Ushio has met a lot of strange things and people, hasn't she?

Thanks to the powers of Google, I could actually translate this one on my own. :P

Whenever I see pineapples, though, I think of Adam Duritz... (http://www.reviewstl.com/wp-content/uploads/2010/09/Adam-Duritz-Photo.jpg)