Invisible

The Invisible (インビジブル) is a sword wielding Pureblood Heartless from Kingdom Hearts and Kingdom Hearts 358/2 Days.

As the name suggests, it has the ability to become invisible. One of its special attacks includes throwing its sword in the ground, while the main body turns into a ring of dark fire surrounding either Sora, Donald or Goofy. Once the time is up, the curse explodes, dealing large damage on any member of the party. Like Angel Stars, they have a high rate of dropping a Gale once you've defeated them.

In Kingdom Hearts 358/2 Days, the Invisible makes several appearances, meant to be an extremely powerful enemy like the Zip Slasher.

Kingdom Hearts
''Heartless wielding a large sword. These winged Heartless can move freely through the air. Besides their sword, they attack with their tail and wings. With their high attack power, they often defeat their foes quickly.''

Kingdom Hearts 358/2 Days
''Both fast and strong, these Heartless pose a serious threat. They attack with a fearsome shockwave.''

''Time your combo finisher so it connects right after they catch their sword. This will cancel the shockwave and leave them open.''

Kingdom Hearts

 * End of the World
 * Olympus Coloseum

Kingdom Hearts 358/2 Days

 * Halloween Town
 * Beast's Castle
 * Agrabah

Abilities
They fire dark energy every now and then. Of course, they will slash at you, but their final attack is to put their sword in the ground, then trap you in a ring of dark energy. This can be avoided by jumping, using Superglide or Dodge Roll.

In Kingdom Hearts 358/2 Days, the Invisible can still perform its basic slash attack, but is given an "improved" arsenal of abilities from its Kingdom Hearts version. Its "Ring of Fire" attack is upgraded to cause its weapon to fly at Roxas up to five times while the beast is invisible, before surrounding Roxas with the ring and striking down with a long-range shockwave as a result. This Pureblood Heartless will fire a consecutive string of energy spheres, dealing a high amount of damage and possibly lowering Roxas's Defense to Lv. 1. It shares all of its abilities with its relative, the Orcus, a weaker, red version of the Invisible.

Trivia

 * The kanji written on its blade means hard shell.
 * Invisibles have a heart-shaped hole in their stomach, much like a Darkside.