Hello everyone.
This manga I've read a long time ago, about a young man who is part of an organization where humans can control robotic personas. He himself isn't completely human and doesn't need to wield any kind of robot, he fights with his own body. His body holds weapons within, notably long blades that he can materialize through his arm/hand.
The art style was pretty simple, not too many facial details, and he had white hair (maybe blonde if the manga was colored). He also lives with a woman who's a bit older than him, and she controls a really creepy persona with long black hair and a dark cloak. She doesn't like tomatoes.
At some point they have to go rescue a cute girl who is kept prisoner by her "father", who is actually her creator and of course, a mad scientist.
One of the characters in the manga walked around in his persona form, so the others didn't know what he really looked like.

Those are all the details I can muster. I hope you guys can help!

A sadist? What? Pshhh!
...
Only a little.
...
Okay, I am.

Is it Hitogatana?