Spur

The Spur (シュプール Shupūru) is the finished version of the Polar Star. It deals one of the highest amounts of damage with a single shot in Cave Story. The weapon can only be obtained by giving the Polar Star to Tetsuzou Kamadani when Quote returns to Mimiga Village from the Waterway.
The Spur was the gun that the Hermit Gunsmith was originally trying to create, but Quote took the unfinished Polar Star from him while he was asleep.
== Location ==
The Spur can be "obtained" back at the Hermit Gunsmith's abode in the First Cave after Quote returns from the Waterway. The player will need either the Booster v0.8 or Booster v2.0 equipped in order to achieve the necessary jumps.
To enter the First Cave with the Booster v0.8, the player should make a running boosted jump from the cage/metal fence at the top of Mimiga Village and make multiple smaller boosts to cover the remaining distance, then use the same method to make the remaining jumps.
To enter the First cave using the Booster v2.0, the player should boost their way up to the platforms hanging from the roof of the cave in the top right corner of the village, jump from them and boost the way on to the hanging platforms in the top left corner, from there, boost the way up to the entrance to the First Cave. 
When the player talks to the gunsmith, he observes the Polar Star is missing and takes it away upon discovering that Quote is carrying it. The gunsmith suddenly feels moved by the evidence of use with the gun, even before its completion. He apologizes to Quote and allows him to keep the gun, after finishing the work on the weapon, which causes the Polar Star to become the Spur.
== Behaviour ==
Unlike other weapons in the game, the Spur has its own charging function, making the weapon immune to damage level-down, as well as making XP unnecessary for leveling up the gun. Holding down the attack button will charge up the Spur's energy and increase its firepower with each level of charge. Its level 1 form bullet does the same amount of damage as the level 3 Polar Star bullet. Fourteen bullets from the Spur can be onscreen at a time. 
== Trivia ==
* If the player returns to the Labyrinth Shop after obtaining the Spur, Chaba gives Quote the Whimsical Star, calling it a "trinket".
* The Spur is considered an "Ultimate weapon" by Chaba.
* After obtaining the Spur, the enemy placement of the First Cave changes. Multiple bats and critters cover most of the ground that were not there before, probably for the player to test the Spur. However, the level 3 Blade seems to be the most efficient at killing these.
*The beams fired from the Spur when charged to levels 2, 3, and Max are the same shape as the bullets fired by the Polar Star at levels 1, 2, and 3, but elongated.