Instructions
Achieve a high hunter rank. Ranks between "E" and "A" do not cause boss levels to become higher, but achieving a hunter rank of "SA" adds two to the Maverick bosses' levels; a rank of "GA" adds four to the Maverick bosses' levels; a rank of "PA" adds eight to the Maverick bosses' levels. Your hunter rank improves by completing stages quickly, defeating a minimal number of enemies and taking a minimal amount of damage.
Drain the clock. The game starts with 16 hours until the collision of a meteorite to the Earth; an hour passes every time you return to the stage select screen from trying a stage. At 16 hours on the clock, one is added to the Maverick bosses' levels; 15 to 14 hours adds three to the Maverick bosses' levels; 13 to 12 hours adds five to the Maverick bosses' levels; 11 to 10 hours adds seven to the Maverick bosses' levels; nine to eight hours adds nine to the Maverick bosses' levels; seven to six hours adds 11 to the Maverick bosses' levels; five to four hours adds 13 to the Maverick bosses' levels; three to two hours adds 15 to the Maverick bosses' levels; one or zero hours remaining adds 17 to the Maverick bosses' levels.
Beat the Maverick bosses. With each boss you defeat, the levels of the remaining bosses are raised by one.