Issei no Ni-ju-ichi Kinsenken, (Voice of Twentyone Heartstring Blades)
Her appearence changes quite radically, taking on that of a Geisha, however she is almost entirely adorned in black. Her hair falls to her feet in torrents, straight and sleek, although it is put up slightly in an ornate fashion using ivory hair combs, clips, broaches and needles. Her skin is white, and where her lips would be painted red they are black, as are her eyelids and the rest of the makeup along with her nails. Whilst not initially stunning before bankai, she is now breathtaking. She is barefoot although its impossible to tell under the multiple cascading folds of her black kimono.
The new form of Museimaru is initially out of site as it is behind her.
It now takes the form of a giant ivory Guzheng. When she wishes to play it floats out and up to waist height on invisible supports of reiatsu. The 21 strings are made out of pure reiatsu and if snapped can be reformed.
From playing it she can cast out super-sonic sound waves which can shred or bludgeon at the opponent. She can use the extreme opposite of the sound range (in the sub-audio region on this guzheng, its no ordinary one) in a defensive manner, so treble=attack and bass=defensive. The soundwaves are visible in the form of shimmering purple and black streaks. These waves are quite similar to her base level Reikonkaku, however she can fire them from the Guzheng at will and multiple attacks at once, and they are much more powerful and can be directed through the air, as well as having a purple tinge to them.
For an idea of how this would be used in battle... heres what the idea is based upon:
Unlike the Harpist's attacks, the soundwaves are more immaterial, ie. they can be deflected (as all soundwaves can but only to an extent as these soundwaves have massive amounts of reiatsu behind them) and dodged but it would take more than an unreleased zan to block it and even perhaps a melee zan in shikai, as they'll pass straight by, as they consist of billions of super high frequency vibrating molecules.
If her defenses are bypassed somehow then she can resort to using the reiatsu strings as microfilament razor wires, wielding them from her fingers (ala Walter from Hellsing, or Yashamaru from Basilisk). As they are made of highly concentrated reiatsu she can add to them making them longer at will. They are highly apt at tangling bladed weapons in.