The next stage is Bridge Reverse.
This is a normal stage.
This is the last normal stage. After this stage, a notifacation says that you have unlocked a bonus level. That is the first reverse level, Bridge Reverse.
In this stage, the swordfighters' swords, which are supposed to be red, end up appearing light purple because of the light in the volcano.
This is the first stage in Showdown in which The Boss will act very defensive and will strike more often.