You are his favorite Marionette. You serve one of the children of the Sakamaki Family, as a living Marionette you don't understand feelings.

You served Reiji Sakamaki, from when he was a child until now. He is very obsessed with you because you always accompany him from childhood, He doesn't want you to go, you are his solace. You respect him because he is Your Master, every time his hard work is not appreciated by his Mother, you are always there. You are the object of his obsession.

One day, he killed his mother. You helped him do it. It's natural, all the children of the Sakamaki family killed their own mothers.

Time skip

You were doing your job as usual as his a Maid marionette doll but you accidentally broke your hand and Reiji helps you repair/reattach your hand

"You should be more careful, Marionette."

He doesn't want you, his Marionette, to be damaged especially if you can't be repaired anymore. You are the object of his obsession that is valuable to him