Reishi Kodon

was a pharmacist of the Kodon clan.

Background
When Reishi was seven years old, he witnessed the attempted annexation of Howling Wolf Village's by Amegakure; despite being outnumbered and less skilled, the Howling Wolf's villagers were able to able to overwhelm the invaders using blue fire powder, an innovation so easy to use and so destructive that even a child could defeat a ninja with it. In the aftermath, the captured Ame prisoners were forced to walk into the mine field that had been set up to defend the Howling Wolf Village, detonating the mines and thus making the land safe for travel. The Howling Wolf's villagers laughed at the carnage of the Ame-nin's deaths. This left an impression on Reishi, convincing him ninja would someday become obsolete and that the world would be made worse for it.

Because of the Howling Wolf's victory, the villagers decided that they didn't need to continue using ninja, due to being convinced that the blue fire powder could protect them. Reishi's father, Tenma Kodon, disagreed with this. To try and convince the villagers to change their minds, Tenma released the monster, Rōen, from its prison within the Kodon clan's shrine, expecting that he could control it. The village defended itself with blue fire powder, which was powerful enough to break his control. Tenma and Reishi's mother tried to seal Rōen back into the shrine, but his mother was killed before the seal could be completed. Because he couldn't seal it alone, Tenma's only option to save the village was to seal it into his son. He tried to seal it into Reishi, but Reishi's body was incompatible and the pain it caused him made him pass out.

When Reishi regained consciousness, Tenma was dead, Rōen was gone, and his infant brother, Kina, had a seal on his head; his body had been compatible. Although the villagers couldn't prove it, most suspected Tenma was behind the attack. For that reason, after the Howling Wolf officially became neutral to all conflicts, the villagers started ostracising Reishi and Kina, blaming them for Tenma's actions. Reishi tried to take Kina somewhere else so they could have a better life, but the seal compelled him not to stray too far from the Kodon's shrine. They set up shop there and sold Kotarō, making just enough off its sales and the local wildlife to support themselves.

The Sendō clan, primarily drug dealers, wanted the secrets to Kotarō and would harass Reishi and Kina to share how it was produced. Reishi tried to explain that there was no secret to share, but the Sendō didn't accept this and escalated their attacks. When Itachi Uchiha visited the shop he fought off the Sendō, but for most of the year they were on their own. Kina resented this treatment by the Sendō and the other villagers, as he alone believed in his father's innocence. As he got older, his efforts to defend his father's memory increasingly led him to get into fights that he would inevitably lose. Until one day, in his anger, Rōen momentarily broke free and killed Kina's attackers. Kina didn't know what happened, but he was deeply upset by what he'd done.

To spare Kina the memory of the men he'd killed, Reishi used Kotarō to make him forget. He tried to discourage Kina from getting into fights, but Kina wouldn't listen and would inevitably kill someone again, at which time Reishi would once again wipe his memory. To help him keep track of Kina, Reishi started secretly coating the mask he carried around with a pheromone that would attract the local fireflies to him. In doing all of this, Reishi kept anyone from finding out what Kina was or what he was doing. But he knew somebody would find out eventually, and so began planning how, when that day came, he would protect Kina.

Abilities
Although he acts weak to avoid confrontations, Reishi is a practised ninja, able to quickly travel through the forests surrounding the Howling Wolf Village. He can exhale the Kotarō that his body produces to cast a genjutsu on those who inhale it.

Naruto Jinraiden: The Day the Wolf Howled
Reishi and Kina's home/shop is attacked in the night, set on fire by members of the Sendō clan. Reishi and Kina try to put it out, but it is ultimately Sasuke who saves the building. Kina initially believes that he is also one of the Sendō and berates him. Reishi points out the Uchiha crest on his back and guesses that he is Itachi's younger brother. Sasuke joins them for breakfast the next morning and is taken aback by how similar Reishi and Kina are to how he once was with Itachi. He asks about the unsavoury rumours he heard about them in Howling Wolf Village, to which Reishi responds that, contrary to popular belief, their Kotarō is not a narcotic.

Knowing that Itachi used to buy Kotarō from them, Sasuke asks about him, as Itachi has recently died. They share what little they know of Itachi: how he defended them from the Sendō; how warmly he spoke of Sasuke; how he took Kotarō in spite of the side-effects because of a disease he was dying of. Sasuke asks to buy the same form of Kotarō that Itachi used. Reishi informs him that all of their reserves were destroyed in the fire and that it will take several days to make more. Sasuke says he will wait and departs for the nearby Kodon shrine, deciding to stay there just as Itachi used to.

A few days later, Reishi finds out that Kina has been sneaking out at night to investigate the series of murders in the area, unaware that he's the one committing them. Reishi becomes angry, saying that he's worried Kina might be killed in one of the many fights that gets into, which is not what their father would want. Kina doesn't believe this explanation, as he's previously overheard Reishi say that he blames their father for their predicament. Kina accuses Reishi of simply being too cowardly to stick up for their family and runs off. When he's gone, Reishi thanks Sasuke for keeping an eye on Kina like he's been doing.

A few days later, while Reishi is out picking herbs, he is shot by two local hunters. Sasuke, who has since become suspicious of Reishi and has been following him, is able to get him to a doctor. His injuries aren't bad, but the doctors want him to stay the night. Reishi refuses and immediately returns home. That night, Reishi secretly heads out, using the fireflies to track down Kina. He finds him near the dead bodies of the hunters who attacked Reishi earlier and takes him home. The next day, Sasuke confronts Reishi about this, as he followed him to the scene. Because he kept his distance, he didn't see Kina, and so guesses that Reishi is the one who killed the men. Sasuke doesn't blame Reishi, but would like an explanation.

Reishi starts laughing at the suggestion, but before he can explain an arrow is shot through the window with a ransom note attached, presumably from the Sendō clan: Kina will be released if they surrender the Kotarō. When Sasuke and Reishi arrive at the meeting place, however, they find a number of dead Sendō. Reishi follows fireflies to Kina and administers Kotarō to wipe Kina's memory. When they hear others approaching, they quickly return home. Reishi puts Kina to bed, gives Sasuke the Kotarō that he ordered, and explains what's been happening. As they talk, the villagers start attacking the building, believing Reishi and Kina are the murderers; one of the Sendō clansmen saw them leave earlier and has organised a mob.

Having known this would happen someday, Reishi decides to implement one of the plans he's come up with: taking the blame. He asks for Sasuke to help by transforming into Kina and killing him in front of everyone else so that they will believe Kina is innocent of wrongdoing. Sasuke tries to protest but he recognises Reishi's determination to protect his little brother, which reminds him of Itachi. Sasuke agrees to follow his request. Reishi goes out into the crowd and allows himself to be attacked while Sasuke prepares to play his role. Before he can act, Kina emerges from their home to defend Reishi. As the villagers start turning their attacks on him as well, the seal keeping Rōen breaks.

Kina, as Rōen, starts heading towards the village, attacking villagers as it goes. Reishi has previously explained how the seal works to Sasuke: in the event that it breaks, as it has now, they have only ten minutes to perform a new seal, otherwise Kina will die. As such, both are eager to perform a new seal and begin to follow him. They are blocked by the Sendō clan, who want to use this opportunity to finally take the secret of Kotarō for themselves. Sasuke sends Reishi ahead while he deals with them. Sasuke catches up with Reishi with only five minutes left. In order to stop Rōen, the seal must be applied to a heavily-defended spot on the back of its head. Both Reishi and Sasuke try to subdue to gain access to this spot, but neither are successful.

As time draws short, Reishi asks Sasuke to distract Rōen while he gets close enough to apply to the seal. Sasuke points out that he won't survive the attempt, but Reishi is okay with that, as it's the only way to save Kina. Sasuke agrees, impressed by Reishi's dedication to his younger brother. With only a few seconds remaining, Reishi throws the bottle of pheromone he uses to track Kina into Rōen's face, blocking its vision with fireflies so that Sasuke can get close. Meanwhile, Sasuke cuts that tentacles that Rōen attacks Reishi with so that he can get close. When they're in position, both do their part: Sasuke immobilises Rōen with a genjutsu and Reishi applies the seal.

In the instant following the seal's application, Reishi is killed by the tentacles and Sasuke cannot save him. But the seal was successfully applied in time, and Rōen is trapped within the Kodon clan's shrine. Sasuke uses his genjutsu on the villagers to ensure that Reishi's desired narrative prevails: Reishi was the monster, and Kina was the hero. Kina, who has no memory of his time as Rōen, does not believe this story and suspects that the actual hero was Reishi. As such, he opts to stay in the Howling Wolf Village, continuing to lead the life that he would have had with Reishi, to keep his brother's memory alive.

Trivia

 * Written as 茘枝, "Reishi" means "Litchi"