I can't find any example of Non-Native Rokugani (besides Naga and Oni) that have the Void Use Feat.
I have looked through at least 10 different Legend of the Five Rings books - All of "The Way..." books and the Campaign Setting book. No Example in Dragon or Dungeon Magazine either.
The only reason I could think of... it is a Setting Specific feat. Could it be adapted outside of Rokugan? Absolutely.
The Void exists in Greyhawk.
The Shugenja core class, pg. 10. While it doesn't have a specific
mention of a feat called Void Use, it does describe the 5th Element
of the Void:
Adventures: Shugenjas often adventure to increase their magical knowledge and personal power. They are particularly drawn to
investigate disturbances in the natural harmony of the four classical
elements (earth, air, fire, and water). Some shugenjas dedicate their
lives to keeping the world’s magic in balance, while others simply
crave the power that the unchecked elements offer. Still others are
drawn to plumb the depths of magic for magic’s own sake, hoping
eventually to learn the mysteries of void, the “fifth element” that
binds the others together. [emphasis: bold]
The Order of Ineffible Mysteries is briefly described on pg. 13:
The shugenjas of the Order of the Ineffable Mystery can specialize in any of the four elements. The Ineffable Mystery also trains
shugenjas who specialize the fifth element, void. [emphasis:
- The Void Disciple prestige class, pg. 72. While it isn't specifically
a feat called Void Use, nearly every power is Void (Insert Text).
- Voidsense. Invocation for warlocks on pg. 136. Warlocks are often
described as channeling the power of fiends. The Oni within Oriental
Adventures are fiends and have lots of lore surrounding The Void.
Rokugan is Designed to be Refluffed
For example, it is noted that while barbarians are appropriate for the Unicorn clan, the barbarian class can be used to represent "beserkers" who are not true barbarians in some Rokugan families. Rangers are also noted as being appropriate to Rokugan, but their spell-casting ability is somewhat out of place. Rangers other than the fox clan and the naga are allowed to take fighter feats instead of access to a new level of spells.
The Inkyo, or enlightened monk, represents a slightly different, less martial monk than the one presented in the PHB. The Inkyo does receive unarmed combat abilities similar to a monk. Their damage progression is slower than the core monk and they do not have the faster attack progression and flurry of blows ability, nor stunning fist or most other standard monk abilities. They do, however, learn how to use "void" points to enhance their rolls or AC, gain a great resistance to elemental magic, and receive a number of free "kiho" feats, which represent esoteric martial arts techniques.
Does that mean PHB Monks should simply be removed from Rokugan? I don't think so. There should be the mix of Enlightened and Non-Enlightened.
What is Rokugan?
Rokugan is just a city-state within an unnamed land mass; savvy DM's could very well adapt that unnamed land mass to certainly be within Kara Tur of the Forgotten Realms.
Gaijin was the Rokugani word for an outsider or foreigner. This essentially meant anyone who was not Rokugani.
Ten distinct nations and regions in Kara Tur1:
- Shou Lung: Imperial China
- T'u Lung: Historical dissident states based in South China during
eras of political disunity (i.e. Nanzhao and Kingdom of Dali,
formerly centred in present-day Yunnan province)
- Wa: Feudal Japan (Edo Period)
- Kozakura: Japan/Ryukyu Islands (Ashikaga period)
- Northern Wastes: Historical non-Sinic tribal societies of Manchuria
or Northeast China
- Tabot: Tibet
- Koryo: Korea
- The Island Kingdoms: Pre-colonial Hindu-influenced civilizations of
Indonesia and the Philippines.
- The Plain of Horses: Historical Mongolia. This region is the Kara-Tur
portion of the Hordelands, also known as the Endless Wastes.
- The Jungle Lands of Malatra: Pre-colonial civilizations of Indochina
(historical versions of the Khmer Empire and Vietnam) as well as the
hill tribes inspired by their real-life Southeast Asian counterparts.
It wouldn't be a stretch to modify the list of nations above to say, replace Kozakura with Rokugan. The Hordelands received some special attention in Dragon #349 with d20 in mind. They are not Rokugani. However, they are within the realm of Oriental Adventures; would be Gaijin; and would/should qualify for Void Use feats.
Black Heart of the Empire2
The Black Heart of the Empire was another name for the Shadowlands, and in opinion of Ide Tadaji should be considered as a part of the Empire.
"Should be considered as a part of..." is a strong implication that the Shadowlands are actually not a part of the Empire - therefore would not be Rokugani. Inhabitants of the Shadowlands are known throughout the source material to have Taint and practice Void Use as well as anyone else.
But the most legendary Courtier seems to think that the Shadowlands should be a part of Rokugan...
Nezumi are native to the Shadowlands:
The nezumi, or "ratlings" as they are often called by humans, are a race of bipedal ratlike humanoids. In Rokugan, they are an ancient race native to the Shadowlands.
Immune to the Shadowlands Taint: Nezumi can never acquire a Taint score, and suffer no ill effects from exposure to the Shadowlands.
If I Were DM...
Personally, I would allow it, but treat it as other Regional feats; if a player not from that region wanted such feats, then appropriate ranks in Knowledge (Local-Rokugan) 5 ranks or so should be a sufficient "requirement."
I personally believe that Nezumi are just as familiar with Void Use as anyone else would be in Rokugan. Therefore, I would allow a Nezumi Inkyo to take full advantage of:
Void Use: Inkyo gain this feat for free at first level.
Learning The Way... in a Different Way
In Rokugan pg. 50, there is a feat available to any and all clans called Different School:
If you remain on good terms with another clan you can learn their feats as if you are a member of that clan. If you are a shugenja you may learn their spells, except for those from an element barred to you. You can take this feat multiple times provided you find a willing teacher.
Throughout history, conjecture aside, there have been traveling masters, courtiers, and ambassadors spreading "the way" (no matter what the subject is) to different societies in order to "get this for that" or whatnot.
A perfect example in recent and in-real-life history is Mitsuyo Maeda settling in Brazil, and teaching Carlos Gracie his Jiu Jitsu. Henceforth, Brazilian Jiu Jitsu was born3.
If a Ghostwise Halfing Monk (...yeah) studied at an appropriate school of such a traveling master, got on good terms, was able to take the feat that allowed a clan technique (of clans that had Inkyo has a class); why not?