Sonic Frontiers just released in November, but it seems that Sega is already working on the next Sonic the Hedgehog game. Director Morio Kishimoto revealed as such on Twitter, and offered an interesting glimpse at Sega's plans for the future. Apparently, the next game in the series will put an emphasis on multiple playable characters, and Sega is looking to expand and refine the "open zones" that were introduced in Sonic Frontiers. Interestingly, Sonic Team wants to avoid overusing classic Sonic locations, such as Green Hill Zone, and Chemical Plant Zone.