Jaken

""Splendid, my lord, splendid. Nothing less than I expected!""

- Jaken

was a kappa demon who is extremely loyal to Sesshōmaru, often praising his master's greatness.

Although Jaken is not nearly as powerful as his employer, he is skilled at wielding the Nintōjō (人頭杖, Staff of Two Heads). He seldom engages in battle and is actually killed by Kaijinbo with Tōkijin, but Sesshōmaru resurrects him with Tenseiga.

History
In the early part of the story, Jaken uses the Staff of Two Heads to find Inuyasha's and Sesshōmaru's father's grave. He eventually became not much more than comic relief, having hardly any role in the story.

Personality
He is smaller than Rin and his physical strength and demon power are weak. It is clearly shown that he is capable of fighting to some degree when he torched the warriors upon Sesshōmaru's orders but he often lets down his guard when he becomes proud, arrogant, or close minded. Classic examples of this are the times when Kagome is able to  take him down by throwing a few skulls or stones.

Jaken has the staff of Two Heads,which bears the faces of a woman and an old man and has a function of detection The staff can also serve as a weapon as the old man's face can spew flame that is powerful enough to annihilate many enemies in an instant.

Eternaly loyal to Sesshōmaru he is sometimes disappointed with compliments that have no meaning and odd jods that offer no reward, but he is proud of Sesshōmaru and puts his heart into everything in order to do his best. He is not willing to take care of Rin, but he shows his loyalty to Sesshōmaru and put his life on the line to obey his master's orders.

Relationships
At first Jaken disliked Rin as she was a human. However, as time went by he began to treat her better. Jaken sometime acts as if he hates her, but in truth he doesn't want Rin to get hurt and whenever there's trouble, Jaken always tells Sesshōmaru to save her. He also worries if Rin gets hurt that Sesshōmaru will kill him. Rin often likes to make up songs such as "Jaken-sama, Jaken-sama, why are you green?" When Rin dies, Jaken is shown crying. Whether they are just for Sesshōmaru's sake, we don't know, but before she died, he was very sad when he found out she was going to.
 * Rin

Jaken respects Sesshōmaru and always praises Sesshōmaru whenever he defeats a demon, much to Sesshōmaru's annoyance. Unlike Myoga, Jaken always sticks by Sesshōmaru's side even when times of danger he understands Sesshōmaru,but even so says things he does not have to say and is punished for it is by getting bump on the head or stepping on him. At times, Jaken may sometimes weep or show sadness for Sesshōmaru. It is unknown whether it is for Sesshōmaru's sake (for he may have an inability to express emotions) or if it is for his own. Examples include when Jaken cries because of Sesshōmaru's "inability to cry" or when Jaken sneezes instead of Sesshōmaru when Inuyasha and his compantion were talking of him, a common Japanese superstition that one sneezes when gossiped about.
 * Sesshōmaru

Jaken and Inuyasha have a very bitter relationship. Despite the number of times Inuyasha has saved him, he always turns against him due to the conflict between Inuyasha and Sesshōmaru. Inuyasha also seems to bully him. As when Jaken started to scold him about Inuyasha calling Jaken "small", the hanyō grabbed him and tried to stretch him out until Kagome told him to "Sit".
 * Inuyasha

Manga vs. Anime
The manga explains little about Jaken's past, but the anime shows that Jaken was once a lord among similar demons (episode 79, "Jaken's Plan to Steal Tessaiga). During battle with another yōkai tribe, the enemy leader had Jaken by his neck when Sesshōmaru appeared and told the demon to move out of his path. When this was not obeyed, he calmly destroyed the yōkai with his poison whip. Out of a sense of obligation, Jaken followed Sesshōmaru, who allowed him to become a servant if he could use the Staff of Two Heads.