From: OnjiIchijo, Akame, Sadame and her Amurita Faith... I wouldn't put my trust in any of them. They're just trying to bargain with you now that they know you're searching for the soul fragments.
But that's to be expected. War in Utakata cannot be avoided, and a ninja like yourself would be a valuable asset to any of them. Of course, this also means that they will stop at nothing to prevent you from being hired by their enemies...
The first thing you need to do is recover your memory. Join up with one of the lords and use them to get information about the whereabouts of the soul fragments.
If you feel bound by past loyalties, you may choose Ichijo. Or perhaps you would rather choose the rich Akame, or even the long shot -- Sadame. You might even pretend to serve all three while waiting to see how the winds of war will blow.
At one time, that was the nature of ninja. Their loyalty was to their mission, and not to a particular lord. They put themselves first in their fight for survival.
In any case, I advise you to think long and hard about the choice you will make.