A new level is coming in mid-July's update called Subterranean Tunnels (mines). It will contain two bosses, "Tranmizer" and "Big Vader".
コロッサスシリーズ Colossus Series (Cast Parts)
Big Vader looks like a huge battleship.
How is he going to fit on regular fields?
地下坑道 The Underground Mines.
[via 4gamer]