Hoshiyomi

was a humanoid demon ninja and a powerful daiyōkai who once fought for good and justice alongside his human love, the female samurai Tsukiyomi, until he was sealed away by her and he began to despise humans from then on.

History
A powerful pair, Hoshiyomi eventually employed Kaijinbō, Tōtōsai's evil former apprentice, to craft a weapon for him, after Tsukiyomi began to show extreme signs of fatigue from their battles. With the bodies of 222 yōkai Kaijinbō forged the Naginata of Kenkon, a powerful sword with a stave in the middle of two separate, yet equally balancing powerful blades. After Hoshiyomi received his prize Tsukiyomi no longer had to fight their common foes, but he struggled with the evil from the sword that was possessing him. Tsukiyomi eventually sealed Hoshiyomi within a pentagram with the intent of destroying the Naginata of Kenkon; however, her plans went awry as fatigue overtook her and she died before she could both destroy the naginata or release Hoshiyomi.

During the story
Decades later, Hoshiyomi was freed and eventually reacquired both blades, one of which Akitoki Hōjō had in his possession to guard, waging war on all of humanity for “its betrayal.” After creating a black hole-like vortex, Inuyasha and Kagome were eventually able to defeat him with the combined power of Inuyasha's Bakuryūha, Kagome's sacred arrow, and a little spiritual help from Tsukiyomi's soul. The Naginata of Kenkon was destroyed along with him by Inuyasha's Bakuryūha. In addition, just before Hoshiyomi’s death, he realized Tsukiyomi's true intent (having begrudged her for sealing him away) of her last actions, forgave her, and, upon his death, was reunited with her by the power of Kagome's sacred arrow.

Personality
Hoshiyomi, in many aspects, was Inuyasha in reverse. Inuyasha originally only sought power, such as when he learned of the Shikon no Tama and use it to become a full-fledged demon, but after meeting Kagome and his other friends, he started to value human life and became more kind: By contrast, Hoshiyomi was originally caring and protected human life, but after being betrayed by a human he grew to despise them and from then on only sought to become more powerful. After his death, Inuyasha even noted that Hoshiyomi was exactly how he used to be before he met Kagome.

In battle, Hoshiyomi has shown reservedness to killing, having the opportunity to slay Inuyasha several times but instead said: "I'll say it again. While this blade means everything to me, it has absolutely no value to you or your friends. If you back off, I'll spare you and the other humans, too. Or do you place no value on your life?". This was odd compared to many other daiyōkai in the series, who wouldn't even give their opponents a chance to run and would simply kill them off without a thought, akin to Sesshōmaru. Further separating him from most daiyōkai was the fact that he seemed to have no real hatred towards hanyō such as Inuyasha, even appeared to view them as equals in some ways. When possessed by the Naginata of Kenkon, however, Hoshiyomi seemed more hostile, calling Inuyasha 'impudent'. Hoshiyomi also had strong human emotions, and fell in love with the priestess Tsukiyomi, and thought that the woman betrayed him.

Tsukiyomi's betrayal hurt him deeply, to the point that when he found out the truth, he refused to abandon his desire to kill all humans as he was too filled with rage. It should be noted, however, that with Tsukiyomi dead, Hoshiyomi didn't have anything else to live for. Indeed, he himself stated that he had gone too far to give up. He also forgave Tsukiyomi after he died and seemed happy to be reunited with her, suggesting that he had been lying to himself the entire time and, in the end, all he truly wanted was peace.

Powers & Abilities

 * Demon Ninja Shadow Incarnation: Hoshiyomi had the ability to create doppelgängers of himself, concealing copy is his true self so that his opponents will attack false enemies. However, this technique didn't work very well when he battled Inuyasha, because the hanyō was able to detect which doppelgänger was the real one by determining which one had a scent.
 * Demon Ninja Shadow Hold: Hoshiyomi throws a dagger into the shadow of his opponent, holding them down by their silhouette and rendering them unable to move. However, when there is total darkness and the shadow is unrecognizable from the rest of the darkness, the technique weakens in power. This is seen when the light of the moon was covered up by clouds and Inuyasha noticed that he could move again.
 * Demon Ninja Pentacle Barrier: Hoshiyomi creates a barrier with a pentacle-star spell, making it impossible to be disturbed. It is left unknown if Inuyasha's red Tessaiga would have been able to break the barrier, as Inuyasha, Akitoki Hōjō and the others were occupied with battling the four demon ninjas. Hoshiyomi dispelled the pentacle barrier when the Naginata of Kenkon was completed, choosing to rely on only the blade for protection.
 * Ball of Light: Much like Sesshōmaru, Hoshiyomi transforms himself into an orb of light when travelling great distances. This is seen when he fled with Kagome as his hostage.

Weapons

 * Sword: The sword he's used before to fight along side with Tsukiyomi to slay 222 yōkai.
 * Naginata of Kenkon: The Naginata of Kenkon was a weapon that was created by Kaijinbō. It consisted of two sharp-edged curving blades going into a tsuba, or hand-guard on either end of a long wooden rod. It was created using the souls of 222 yōkai.
 * Aura: Giving off a dark purple malevolent aura, the demonic essence of the Naginata of Kenkon was powerful enough to corrupt and possess (as Tsukiyomi suspected) Hoshiyomi, forever changing his personality until his death. In one particular scene of note, Inuyasha was exposed to the unshielded aura of the Ken blade, while it was still in the possession of Akitoki Hōjō. In that scene, it appeared that Inuyasha lost himself completely to the evil influence of the blade, unable to hear the voices of his friends calling his name. It wasn't until the blade was covered again that Inuyasha returned to himself, unsure of what had just occurred. This event demonstrated the evil corrupting power of the Naginata of Kenkon, and showed exactly the kind of influence that Hoshiyomi had fallen under.
 * Barrier: Even with just the Kon blade, Hoshiyomi is still able to erect a yellowish barrier, exceedingly strong and powerful enough to withstand the power of Inuyasha's Kaze no Kizu.
 * Energy Absorption: At least attributed to the Kon blade, the Naginata of Kenkon is able to absorb both demonic energy, as seen in the instance with the Tessaiga and spiritual energy such as seen in the instance with Kagome. In addition to this, the Naginata of Kenkon is able to emit this energy as a Kenatsu, shown when Hoshiyomi fired a blast at Inuyasha right after absorbing much of the Tessaiga's demonic energy. The energy absorbed from Tessaiga was comparable to Sesshōmaru's first use of the Kaze no Kizu. This ability is quite similar to Inuyasha's Dragon-scaled Tessaiga.
 * : Kenatsu is the special ability that allows the Naginata of Kenkon to cut an opponent with its yōki without physically touching them.
 * Crimson Sphere: It is one of the Naginata of Kenkon's strongest offensive attacks. It takes the form of an extremely huge crimson sphere of pure energy and can be directed at an opponent. If said attack connected with someone, the sphere would engulf them and quite possibly exterminate them into nothingness. Hoshiyomi used this as a seeming last measure attack to kill Inuyasha and his group.
 * Spherical Shockwave: Similar to Sesshōmaru's spherical shock wave with the sword, Tōkijin, a highly destructive sphere of demonic energy is created on the tip of the blade and disperses in a spherical fashion. Hoshiyomi used this attack to slay a large number of yōkai in one stroke after they had surrounded him. This event is similar to the Kaze no Kizu which, could destroy a hundred yōkai in a single swing.
 * Nether Vortex: Quite possibly the Naginata of Kenkon's most powerful technique, and quite similar to the Meidō Zangetsuha, the "nether vortex" is a form of red kenatsu burst that theoretically creates a portal to the invisible void between Heaven and Earth. This portal, however, also acts similar to a black hole in that it sucks in everything around it with irresistible force, similar to Kazaana. Being the space between the most powerful forces in the universe, it is speculated that with enough time that the black hole could absorb the entire world into itself. That would benefit Hoshiyomi's goal to destroy every human in the world and that could be the reason why he used such a dangerous technique.

Allies
Hoshiyomi loved Tsukiyomi a great deal, to the point that he even changed his name to show how much he cared about her. After seeing how exhausted she was getting, Hoshiyomi became very worried and so created a weapon known as the Naginata of Kenkon to protect her. It was also clear that Tsukiyomi loved Hoshiyomi just as much he loved her, as she easily risked and, in the end, sacrificed her own life in order to free him from the Naginata of Kenkon's corruption. Even though it was to save him, she still considered what she did to Hoshiyomi as a betrayal. Upon learning the truth, Hoshiyomi began to wonder if the true reason for his creation of the Naginata of Kenkon was that his heart didn't have faith in her. Just before his death, he forgave her, and, upon his death, was reunited with her in the afterlife.
 * Tsukiyomi

Not much is known about Hoshiyomi's relationship with his underlings, but it was clear that he considered them reliable, frequently dispatching them on tasks that he could easily have done himself. However, he seemed indifferent towards their deaths, suggesting that, in the end, he only saw them as tools towards his ultimate goal.
 * Byakko, Suzaku, Genbu & Seiryū

Enemies
Even though they were enemies, Inuyasha was able to see himself in Hoshiyomi due to the fact that the latter was exactly how the former used to be. Hoshiyomi can also be seen as a foil to Inuyasha's father, Tōga; both were daiyōkai who fell in love with a human and forged a weapon to protect them. However, while Tōga had his weapon forged by Tōtōsai, Hoshiyomi had his forged by Kaijinbō, and in turn was unable to control it.
 * Inuyasha

When Kagome awoke in the Furai shrine, Hoshiyomi questioned why she was travelling with Inuyasha, wondering what a human could possibly mean to a hanyō. He immediately dismissed their bond as one that would not last, convinced that one day, Kagome would betray Inuyasha. When Kagome retorted that she would never do that, Hoshiyomi countered with his opinion of humans, describing them as weak-willed creatures who betray others in order to protect themselves. These words merely convinced Kagome that Hoshiyomi didn't understand humans at all.
 * Kagome Higurashi

Trivia

 * He is similar in appearance to Menōmaru. Both were also killed the same way.
 * His ability Demon Ninja Shadow Hold is similar to the ability of Shadow Possession Jutsu of the Nara Clan in Naruto. In the Shippuden series, character Shikamaru Nara charges a Trench Knife with his chakra to freeze Hidan and Kakuzu of the Akatsuki in place.
 * His seiyū, Kazuya Nakai, later voiced The Wandering Power Stone from Rumiko Takahashi's newest series 

Media appearances
Hoshiyomi Hoshiyomi Hoshiyomi 星黃泉