For fans of two-piece swimwear, it’s like Christmas in July.

Japan has one official holiday in July. Marine Day, or Umi no Hi as it’s called in Japanese, is held on the third Monday of the month, and is a nice midsummer excuse to blow off work and head down to the beach.

There’s another day of celebration during the month, though. On July 5 Bikini Day marks the date when the world’s first bikini was unveiled back in 1946. Bikini Day may not be an exclusively Japanese observance, but given the country’s unabashed love of sexy fashion, it’s especially popular among models in Japan, particularly those in the gravure/gurabia genre who specialize in revealing outfits.

As such, July 5 say a flurry of bikini-related social media posts in Japan, with models such as Yu Kanawa…

…Ayaka Ozaki…

…and Megumi Okamura, who’s also a vocalist attached to uniformly busty idol unit KNU, sharing swimwear snapshots.

Popular model Jun Amaki decided to share a few photos of herself in what almost looks like a one-piece…

…but is, in fact, her bikini bottom worn on her chest and the top on her hips.

While some contributors, like Kie Inoue (also of KNU) took the opportunity to tweet fresh photos…

, others took the “greatest hits” approach, sending out composites from multiple bikini-wearing sessions, such as these from Yuno Mizusawa…

https://twitter.com/mizuyuno_/status/882552774977650688

…and Aimi Sekiguchi.

Bikini Day was accompanied by more of a flurry of activity on Twitter than Instagram, but some also took to the photo-sharing site to take part, such as Yu Momose.

The day was also a popular time for selfies, though Nana Sakuragi…

https://twitter.com/nana_sakuragi/status/882404326353678336

…and Hikaru Aoyama seem to have had some trouble keeping their faces in frame…or simply assumed their fans’ eyes were going to be drawn elsewhere anyway.

Bikini Day doesn’t lend itself all too easily to cosplay, seeing as how many bikini designs have only the bare minimum of fabric to work with. Still, dedicated fans managed to dress up as KanColle’s anthropomorphized American battleship Iowa…

https://twitter.com/momoreku/status/882581928947236864

…Super Sonico (who basically wears a bikini 365 days a year anyway)…

https://twitter.com/Rifu_PR/status/882405942947528704

…and Fate/Grand Order’s Sukasaha/Scathach…

Speaking of Sukasaha, she also got a 2-D Bikini Day salute…

https://twitter.com/sendrawz/status/882630698577809409

…as did Re:Zero’s Rem.

Even bikini armor showed up in the festivities.

▼ Leda’s Yoko and Valis’ Yuko? It’s an ‘80s anime-style swordswoman nostalgia overload!

Bikini Day has officially come to an end in Japan, where it’s now July 6, but the celebration continues on social media where photos continue to trickle in with the hashtag #ビキニの日.

Source: Twitter/#ビキニの日, Hachima Kiko, IT Media
Featured image: Twitter/@reikaya66