Itsuki is arguably Sensui's closest right-hand man...erm, youkai. A rare Yaminade (literally, "one who strokes the darkness"), Itsuki has six extra hands that are controlled independently of his person, along with an Ura-otoko ("Man-In-Reverse") he keeps as a pet. He is also responsible for forming the tunnel to Makai, and can trap beings within a subspace/Limbo-type dimension that he alone controls.
Itsuki is also extremely loyal to Sensui. He says that he has a "pure soul" since the proof is that it has become tained with madness [I WORSHIP the paper analogy!], and is also in love with him (OK, more accurately, his original "Shinobu" persona that he met in the "TV show" incident). There is debate among fans as to whether or not Itsuki's affections are one-sided; however, in the uncut dub, it is made fairly explicit:
"He has everything. Sensui can be violent, courageous, spiritually pure, and even fragile. He can be a graceful spokesman with charisma to bring anyone to his side. Indeed, I have been drawn to his aura like a moth to the flame since the very first moment that we met. I first saw him in the darkness, forging a path of light. I would follow him for hours, unbenownst to him. Just watching him work made me feel alive....
'...And so he let me live. I was his first step in realizing his relationships between good and evil could not be so...'traditionally defined'. ...
''Who could have dreamed that this hunter I admired for physical prowess, this killer of killers, could also be warm, compassionate, intellectual, open to broadening his view of the world...Yes, I admit my attraction was not merely academic; I always wished he would become my lover."
(Note the double entendres in the English dub..."traditionally defined" as in human/demon can also mean the supposed good/evil split in Western culture [for which the dub was adapted] between het and same-sex relationships. ^___^ Especially the way Itsuki's NAVA SAYS it. [Just an idea.]) (In Japanese, of course, this is a lot more vague....you're not quite exactly sure if "I felt like I had obtained a time bomb and a lover at the same time" is meant to be literal or metaphoric, if it's just in Itsuki's head or if it really happened. However, the rest of his Japanese speech is really sweet and heartfelt^^.)
...The fact that Naru-chan exists and only appears around Itsuki I take as a sign that the two of them have let their defenses down around one another, quite possibly due to intimacy between them. (Plus in the dub, Itsuki says that Naru wakes up crying to him at night...I wonder why s/he would be so near him AT NIGHT? *ahem*)
Also...the scene where Sensui dies makes me cry...Itsuki carries him off to Limbo as per his final request that Reikai not take his soul, and what results is truly one of the finest scenes of love I have seen in an anime. It's so final, and yet...both of them get some peace of mind.
I have to admit I am biased, as S/I is my One True Pairing; however, there had to be a section on the relationship, just like every Yuusuke shrine worth their salt should have something on Keiko as well.
By Me
"Comfortably Numb"//Fan Soundtrack (at LJ)