Sergeant

The Sergeant (yes, the capitalization is necessary) is the leader of the Alpha Team (with passion~ and camaraderie~) of Rangers in Earth Defense Force 5.

General
The Sergeant and Alpha Team get one of the more dramatic introductions as they are the one to bail the player character out from potentially fighting a giant ant with their bare fists (even if that would be pretty awesome). After sussing them out as a civilian, Sergeant gives the player character a set of weapons (it is best not to think about precisely why he would be carrying equipment for all four soldier classes around with him), basic gun training (aka a tutorial), and escorts them out of the base. After several attempts to escort the player character to safety end in increasingly dangerous situations where they (hopefully) demonstrate a measure of combat ability, they invite the civilian to officially enlist with the EDF (and get the Wing Diver a jetpack that doesn't look like a science fair reject).

He later manages to acquire a powerful prototype weapon, the Blazer, which he attempts to use to take down Archelus. However, the creature proves too resilient for even this new device, forcing the EDF to come up with a new plan. The Sergeant notably does not return the Blazer and uses in almost every mission he appears in for the rest of the game.

During the operation to reclaim Base 228, the Sergeant along with his team, the Spriggans, the Grim Reapers, and the player character(s) are all joined into a single unit; Storm Team, with the Sergeant taking on the callsign "Storm 2."

Gameplay
The Sergeant and Alpha Team don't act very different from any other Ranger unit the player can recruit on the field, though depending on the mission they may have a lot more health than normal NPC Rangers. The primary difference, though, is that somehow, he and his team are incapable of dying permanently. Normally when an NPC soldier's health is depleted, they die and disappear after a while. The Sergeant and Alpha, however, drop to one knee and will get back up after either a certain amount of time has expired or a dialog event triggers, with 25% of their health restored. It's unexplained exactly how they're capable of doing this in storyline terms.

This status is sometimes also extended to other units, particularly guides in underground missions, as well as the other special units Spriggan and Grim Reaper (mostly only Spriggan Leader and Grim Leader rather than the whole unit), though at other times they are treated as completely normal NPCs who can die like anyone else.