Olfactory Genjutsu

Olfactory Genjutsu remains one of the rarest forms of yin release used to initiate genjutsu attacks on opponents. Though unusual it is an effective method of delivery often used as a supplemental tactic in Kyrgyzishi Clan attack patterns. The versatility of this style of attack lends itself well to many different combat strategies. As the Uchiha were the primary impetus for the creation of this style of genjutsu it remains particularly effective against members of this clan, as well as many other types of doujutsu users.

History
The Kyrgyzishi developed this style of genjutsu after their initial defeat at the Uchiha's hands during the Ten Fingers of Blood Stained Hands massacre and their subsequent dealings with Hidden Mist. These techniques were developed to mimic both the Hiding in Mist Technique and Clam based genjutsu that worked so well against the Kaguya Clan as a counter to the Sharingan in future conflicts. Shodaime Oyabun's experiments with weaponized Baku and Ōnyūdō pheromones led to the creation of various aerosolized delivery methods.

Usage
The user releases a fragrant or malodorous gas, mist, fog, aerosolized chemical, particulate, or other substance into the immediate environment. Any target with functioning olfactory receptors who inhales the odorants emanating from the attacking substance finds the user's yin chakra invading vulnerable cerebral structures. The target's sense of smell becomes the pathway for delivery of the invasive chakra and initiation of genjutsu. Without intervention susceptible subjects fall under the user's genjutsu.

Advantages
Olfactory Genjutsu has several advantages over other types of delivery methods:
 * The Genjutsu is continuously applied as long as the substance remains ambient in a certain location. Targets who break out of the genjutsu can find themselves pulled right back in without an effective counter.
 * It is particularly effective against targets with enhanced olfactory reception, such as those in the Inuzuka Clan.
 * Most delivery methods in this category facilitate camoflauge tactics, similar to those used by shinobi from the Hidden Mist.
 * Can be delivered in a time release fashion so that genjutsu only initiates upon saturation of the targets respiratory system or on remote trigger from the user.

Risks
Genjutsu delivered through the sense of smell has notable weaknesses:
 * Since it is designed to be detected, it will initially tend to give away the user's location to a target with at least Kakashi's level of scent tracking ability similar to sound based genjutsu. This can be alleviated to a large degree by remotely triggered odor sources or immediate relocation. However, that requires some amount of preparation which may not always be opportune. This is only a problem if the user wishes to remain hidden in the first place.


 * Odor based genjutsu is as susceptible as sound based genjutsu to interference from wind based counterattacks. Again this weakness can be somewhat mitigated by large AoE coverage so that vacuum from the wake of wind gusts drags in as many odorants as are repelled. Thus eliminating most kinds of wind based counters. However, this is a particularly chakra intensive solution.

Targets without functional olfactory receptors or those without vulnerable cerebral structures, such as Aburame insects, remain immune to the effects of these delivery methods.