This contains spoilers from the Manga that have not yet appeared in the Anime.The mysterious Nemu Takara does his best to remain unnoticed, but he may play a vital role towards Rin's destruction in future episodes of Blue Exorcist. Blue Exorcist tells a supernatural story of the son of Satan, Rin Okumura, as he goes through his training at the True Cross Academy to become the ultimate demon hunter and end Satan's life once and for all.
But first, he needs to learn how to control the formidable Blue Flames - Rin's blessing, and his curse. After much trial and error, the young Exwire eventually realizes that he needs to accept his classmate's help if he is to be successful. While making friends come easily to the demonic Exorcist, nobody is quite certain about where Nemu Takara's alliances lie.
Who is Nemu Takara?
In this popular shonen anime, viewers are not given much information about the strange Exorcist, Nemu, done purposefully to add to the air of mystery surrounding him, and intriguing fans even further in the process. The sleepy ventriloquist always skirts the side-lines of any drama or event, only "speaking" for the first time after several episodes. The peculiar youngster communicates solely with the use of a puppet (a pink, unnamed rabbit being his favorite), and he appears to be half-asleep at all times. Nemu doesn't leave much of an impression on his classmates until the Training Camp arc, where he surprises everyone by being the first to return with his Peg Lantern - the rest of the squad had to work together as a team to maneuver their lantern back to base.
The skilled swordsman and unconventional teacher, Shura Kirigakure, is the first to grow suspicious of the puppeteer Exorcist, and eventually confronts Mephisto Pheles about Nemu's enrollment as an Exwire. It is revealed that the demonic Principal hand-selected Nemu to join the ranks of the True Cross Acadamy - and alarm bells immediately go off. Mephisto is clearly scheming, to what end fans are still uncertain, but they do not doubt that his intentions are sinister. All roads lead to the manipulation of Rin and his Blue Flames, but now the mysterious side-character and his pink rabbit may play a more vital role than initially anticipated.
How powerful is Nemu?
How was it possible for Nemu to single-handedly return his Peg Lantern, while the others struggled even after joining forces as a team? Fans who were unable to wait for the supernatural anime to reveal more details about Nemu hit the books, and the Blue Exorcist Manga left them pleasantly surprised.
Only posing as a slightly-capable Exwire, Nemu is in actual fact an Upper First Class Tamer, putting him in the same league as Igor Neuhaus, Shura Kirigakure, Uwabami Hojo, and Yaozo Shima - the top dogs in the True Cross Order. So why is such an experienced Exorcist masquerading as a student, under the direction of Mephisto no less? The Principal reveals that his main goal for Nemu is to keep a close eye on the students at the True Cross Academy, Izumo Kamiki in particular.
Is Nemu's Puppet Sentient?
When considering his impressive powers as an Upper First Class Tamer, one needs to take a second look at Nemu's pink rabbit and reassess the ventriloquist assumption. As a Tamer, the self-proclaimed Puppet Master has the ability to invoke familiars into inanimate objects, with dolls and puppets being his preferred choice. Nemu can then send his dolls out to do his bidding by gathering information, tracking people, or even fighting in his place. This, however, begs to question - if Nemu is seemingly always asleep, is the Pink Rabbit familiar the one really running the show? In the True Cross Academy Festival arc, not only does Nemu initiate his first battle but also opens his eyes for the first time - startling his opponent, Renzo Shima, to the point where he withdrew from combat. However, the wide-eyed Tamer is immediately encouraged by the Pink Rabbit to return to his slumber. This suggests that the only character that viewers have gotten to know over the past 2 seasons may be the familiar who possessed Nemu's puppet, and not the boy himself. It also seems that the power dynamic between familiar and Tamer is leaning heavily in favor of the demon, leavings fans questioning who is really in control here.
It is quite suspicious that when the other Tamers summon their familiars, viewers are usually provided with the demon's name - for example, Izumo has her foxes, Mike and Uke, Shiemi Moriyama is never far from Nee, and Renzo Shima with his fiery Yamantaka. However, the demonic familiar imbued within Nemu's Pink Rabbit has yet to be identified, which can only be deleterious, because why else would it be such as secret? A fan-favorite theory is that Mephisto himself is somehow controlling the familiar behind the rabbit, or actually is the demon possessing the pink critter - making Nemu the pawn and Mephisto the ultimate Puppet Master of Blue Exorcist. Whoever controls that bunny will undoubtedly play a significant part in Rin's future as an Exorcist.