See those signs? They read, "Majikon" — Japanese for R4. And they are pointing into a random apartment building.
Nintendo leading the legal charge against the R4, even asking individuals to anonymously rat out retailers selling the devices. One Akihabara R4 retail shop recently closed due to "adult reasons" — some on the Japanese internet are inferring that the heat from Nintendo has caused the store to shutter.
R4 cartridges are used to pirate Nintendo DS video games.
This Den-Den Town "store" in Osaka is advertising its R4 wares with a sign board that reads, "These products are not illegal." The R4 exists in a grey area legally. There's a court injunction against the Chinese R4 makers for "violation under Japan's laws". Last year, Nintendo (and 53 other software companies) took action against the makers of the R4 cart.
Osaka is already home to the R4 vending machine.
Signs in the apartment building direct customers to the "shop".
This is not to say that R4 devices are not being sold openly in cities like Osaka and Tokyo, because they are. But for how long?