Geist

The Geist (ガイスト) is a Tamakoma Branch-exclusive trigger, and Kyōsuke Karasuma's personal trigger.

Appearance
The Geist appears as a partial armor, which covers the user's legs and right arm, and also other triggers they may be using, such as the Kogetsu.

Large-Scale Invasion Arc
Karasuma first used Geist's Blade Shift to try battling Hairein, but the latter used Alektor's Trion fishes to protect himself, rendering Karasuma's attack useless. Karasuma then changed to Speed Shift to attack Hairein before he escaped with Mira, but Hairein used Speiraskia's portals to attack Karasuma from behind, forcing him to bail out.

Abilities
The Geist increases the user's strength and speed, and also their other trigger's powers. Geist has different modes, or "shifts", which increase a different skill. The only known ones are Blade Shift and Speed Shift. This incredible ability causes the trion to become unstable, forcing a bail-out after a few minutes.

Trivia

 * "Geist" is a German word which can mean "mind", "spirit", or "ghost".