Japan is famous for its service. Waiters and waitress are attentive and prompt, and they don't even expect a tip! It's very easy to get accustomed to. But sometimes good service gets old. Sometimes otaku just want to be treated like crap.
Enter the tsundere cafe, where folks pay money to be treated like dirt. Maid cafes hit big in Tokyo's geek paradise Akihabara around 2003 and 2004. They were offshoots of pie-house Anna Miller's, which was a proto-maid cafe of sorts. Today, the popularity of Anna Miller's has subsided, but the uniforms worn by Anna Miller's waitresses are still iconic, inspiring costumes in countless video games, anime and manga.
As maid cafes increased, they tried to differentiate themselves, with some maid cafes going as far as offering video games play sessions with maids - for a price! The maid cafes were and still are, in many ways, the geek equivalent of hostess bars.
There is an array of sexual services offered in Japan, and the point here is not sex - but rather to talk, awkwardly flirt and perhaps play paper, rock, scissors. By comparison, the point of hostess bars is often to complain about work, get horribly drunk and have a lady in evening wear pour your drinks and light your cigarettes. Of course, there are customers who try to sleep with hostesses - and there are hostesses that sleep with customers (or even marry them!). But generally speaking, the point here is talking and flirting.
And just as there are host bars for women, butler-themed coffee shops, like the foreigner-staffed Butlers Cafe, for female nerds started appearing in 2006. One cafe even had females dressed as male butlers, serving female clientele. But as the maid (and butler) cafes became increased, they became more niche.
In 2006, Akihabara maid cafe Nagomi started having "tsundere" events as the concept of "tsundere" became more and more popular. Popularized by visual novel Kimi ga Nozomu Eien, "tsundere" characters are cold, even mean at first, but gradually become clingy. That's why waitresses at Nagomi don't say "Welcome, Master" like at other maid cafes, but "What are you doing here?"
During the tsundere events, customer orders are ignored with the maids saying, "That's a real pain in the ass." Instead, the maids bring whatever they want, which might be a glass filled with coffee beans to whatever gross-looking concoction they've made. And when they bring the drinks, the straws are usually chucked on the table, along with a bag of potato chips.
Nagomi bills itself as a "little sister" cafe, so during the tsundere events, the maids turn into feisty little sisters, who totally hate their big brothers - and in turn, the customers. It's all a gag, and the customers are in on it. That doesn't mean the waitress can always stay in character - as evident when Osaka-based comedian Kazutoyo Koyabu heckled a Nagomi maid, causing her to break out in laughter.
But when customers leave, the tsundere character suddenly becomes clingy, asking if the customer is leaving and going to a maid cafe because she's been mean. This is precisely why the tsundere events are popular - the clingy moments at the end, right after being a total pill. It's all somewhat masochistic, but the unpredictable nature of the tsundere events makes them popular with customers.
The staff at Nagomi aren't always mean, mind you. Why next week the theme is dressing up in wedding dresses. So if you've always wanted to go to a little sister cafe and be served rice omelettes by a lady in a wedding dress, here's your chance.