Not much is known of their story or involvement in the storyline but it is presumed that they are enemies of King and his Knights. It is also possible that the Killer Beekeepers simply don't like people on their bee farm, and are just trying to chase away any intruders.
Summons a bee that drops straight down from the sky, stinger first, until it hits an enemy or the ground, at which point it dies and bounces off the ground a couple times before blinking out. Each upgrade level adds another bee that drops just in front of the previous ones.
This is the only splash attack that deals normal damage to targets in the air.
Because the bees fall straight down instead from the sides similiar "Arrow Rain" or "Weapon Rain", it is easier to hit many bosses with all of the bees compared to those spells, making this one of the best Splash Attacks for hitting airborne enemies. However, because each bee dies as soon as it hits something, each bee can only hit one target, whereas in most Splash Attacks each hit of the spell can actually hit multiple enemies. Thus it is limited to hitting 7 enemies at most, whereas other Splash Attacks have no upper limit to how many enemies they can hit (just how many hits they can do to a single enemy).
If a boss is next to or floating next to a wall (e.g.: the last boss in his floating spider form) and you use Killer Beekeeper's splash attack next to or under the boss, the bees will come down in a straight line, ensuring every bee is dealing a hit and causing tons of damage. It works well if whomever the boss is chasing holds up their shield next to a wall while the designated Killer Beekeeper splashes away.