Interesting, would his Zanpakatou be Benihime, or Kisuke himself?
Vampire anime/film (take your pick, or generalise)
This is more of a Zanpakatou concept, so feel free to decide which Vampire Ichigo has imprinted on.
Sealed Form: Katana, Blood red Saya and Wrappings. Fanged Tsuba design.
Shikai Call: Drink, Vampyr.
Shikai Form: The blade grows small, thirsty fangs the size of fine needles, they lick out of the edge when an opponent is cut.
Shikai Abilities: Opponnents cut with this blade have their' reiatsu drained continuously by a slowly thinning connection with the blade, this weakens them and strengthens the wielder, also providing some protection from that persons Kido (similar to Apoll Grantz(sp?), he becomes adjusted to the enemies 'frequency' and can better defend against it.
Bankai Call: Consume, Wamphirii.
Bankai Form: Blade turns blood red and grows, a trailing thin trickle of blood flows from the hilt, adding a time limit to the Bankai. The Shinigami's Kimono turns blood red as does their' eyes.
Bankai Abilities: Beings with spiritual powers slain by this blade are absorbed, consumed by the wielder leaving their' knowledge, abilities and even their' Zanpakatou's the property of the wielder as their' spirits are enslaved within the wielder's inner world.
Note, to prevent twinking this ability has two major hindrances.
1: The victim is chained within the inner world, however they must be convinced to share their' skills with Ichigo. The problem is that the chains only hold them as long as Ichigo's will is greater than theirs', they can essentially challenge Ichigo to become the king; though only once and only one at a time. Defeat means absorption into Ichigo's greater spirit, granting him their' knowledge, abilities and reiatsu. However, Ichigo places his soul as the wager, if he looses, their' places are reversed. Note that this challenge need not be combat, it could be will, a riddle, a game of chess, etc. But both agree beforehand on the forum. (might be fun to see zanpakatou cheerleaders!)
2: The victim's Zanpakatou is brought with them, and following Ichigos absorption of their' former wielders, he may manifest them sealed and go from there. While it is not impossible for him to attain multiple bankai, in theory, in practice that would be extremely difficult as the Zanpakatou is not attuned to Ichigo's personality like his own, and would take far more work to earn it's respect.
EG> Ichigo defeats and kills Byakua, who is drawn soul and blade into ichigo's. Ichigo must then claim his soul (described above); he may then call meet Senbonzakura for the first time, manifest his/her blade and try to earn the Shikai/Bankai.