Wig

A wig, short for periwig, is a type of head covering that superficially resembles hair, often worn for religious or ceremonial purposes. It utilizes various sources, including horse hair, yak hair, buffalo hair, donated human hair, and sometimes wool, feathers, or synthetic materials.

While reflecting on Raiden and his rescue of her during her crossing the Strut L Oil Fence on the Big Shell in 2009, Emma Emmerich briefly speculated that Raiden's hair was actually a badly done wig because of its unusual appearance, although she wasn't sure whether to ask him due to thinking it would anger him. Raiden, having overheard her comment via a directional microphone, then contacted her via Codec and informed her that his hair was in fact real.

Behind the scenes
Wigs appeared in Metal Gear Solid 2: Sons of Liberty and Metal Gear Rising: Revengeance, where they acted as Raiden's equivalent to Snake's Infinity Bandana. In the former game, there were three different wigs that Raiden could wear that bolstered certain traits to infinite usage. In respective order, the brown, blue, and orange wigs supplied the player with infinite ammo, an infinite O2 gauge, and an infinite grip gauge. In the latter game, two wigs, called Infinity Wig and Infinity Wig B, were unlockables, which allowed for infinite ammo for sub weapons and infinite blade mode, respectively.

Besides their appearance in the aforementioned games, they were also utilized in Metal Gear Online, where the player could supply their character with pigtails, a mohawk, a ponytail (male and female varieties), and an afro, which each allowed for the natural haircolors of black, white, gray, red, brown, and blond(e). Unlike the aforementioned games, they do not bolster the player's stats to infinite levels, and are solely used for decorative purposes only.