Man that'd be awkward if Kirigakure ever found out Konoha was sheltering one of their rogue ninja with one of their national treasures within their black ops organization. Might even spark a war or two!
But really I'd rather you didn't since that would properly shatter my suspension of disbelief if he and Chigetsu were on the same team without Chigetsu taking the sword back.
Besides, experiments are more fun anyway. I mean, look at all those Orochimaru volunteers!
That's why I suggest the character has made amends with Kirigakure before joining Konoha. The two are close allies and wouldn't harbor the rogue ninjas of the other.
I'm assuming Chigetsu is the name of your character? In any case, he'd probably be chastised for stirring up conflicts in the ANBU XD
You get the cool curse mark though!
Do I have to use the swords from the manga or could I make use of a self-made one?
Yes on custom swords. It's encouraged even.