Miiverse

Miiverse was a social network application created by Nintendo and compatible with two of its consoles, namely the Wii U and the Nintendo 3DS, intended to facilitate conversation about games on said consoles. was among the games compatible with the service, allowing players to post messages that would appear to other players.

Miiverse was not compatible with the Nintendo Switch, and the service was shut down on 2017-11-07. However, and  feature a similar posting system to replace it.

Description
Players could post to Miiverse's Splatoon community using the mailbox in Inkopolis Plaza, either with text or a drawing, both of which were created on the Wii U GamePad. Posted drawings could appear as graffiti or on billboards in the plaza and in all stages, and both drawings and text posts were displayed in speech bubbles that would appear above approached Inklings in the plaza. During Splatfests, the number of Miiverse drawings seen in the plaza would increase, as they would adorn a variety of objects, including fireworks, neon signs, and the backs of the Squid Sisters' trucks. When zooming in on a post in the plaza or using to examine the Inkling who sent the post, a player could "Yeah!" a post by pressing. Each post would track how many players had Yeahed it, though there was also an "Unyeah" option allowing players to remove their Yeahs (however, this option was available only from the Miiverse application itself, and not directly from Splatoon). All Miiverse posts were categorized depending on which of three regions (namely North America, Europe and Oceania, and Japan) the poster's system was set to, and a player would only see posts corresponding to their respective region.

Miiverse posts could be hidden in the Options menu, which would remove all speech bubbles above Inklings in the plaza and replace other appearances of posts with placeholder illustrations. Disconnecting from the internet, not having a Nintendo Network ID, or having Miiverse disabled in the system's Parental Controls would have the same effect.

Closure
Miiverse was shut down on 2017-11-07. Since this date, Miiverse posts no longer appear in the game, with speech bubbles above Inklings in the plaza being removed and other appearances of posts being replaced with placeholder illustrations (the same effect as choosing to hide posts in the Options menu, disconnecting from the internet, or otherwise disabling usage of Miiverse would have produced originally). The mailbox also stopped being functional and attempting to use it causes an error message to appear, reading "The Miiverse service has ended. Miiverse and any software features that make use of Miiverse will no longer be available."