The magazine has confirmed that Sonic Mania Plus will release on July 19, 2018 in Japan priced at 4,490 yen on PS4 and Switch. What makes this a little interesting is that the Western release is still listed as Summer 2018, so we can expect it to be around the same time the Japanese version comes out.
Sega also teased a new trailer that will release later today:
New trailer tomorrow! pic.twitter.com/K7PZV5rYsu
— Sonic the Hedgehog (@sonic_hedgehog) April 24, 2018
Those who own Sonic Mania in Japan will be able to get the added content in a 500 yen DLC. This also applies to those who own the game on Xbox One and Steam in Japan.
Sonic Mania is available on PlayStation 4, Xbox One, Nintendo Switch, and PC.