I based it on early Bleach Volume covers hence the multi-colored name. The name itself comes from the fact that "Tatsu" stands for "Dragon". The Colors represent the different colors that a Karate Belt has.
It's Volume 7.5 because it's supposed to take place in-between the events of Volume 7 and Volume 8.
You say yours, but do you mean that like only you get to kill him? Or something else?
“Yes.” Esdeath replied without clarifying of her intentions toward the poor fledgling vampire who still was fleeing and hiding from her determined pursuit.