Any 5 month old puppy is going to be full of energy. You're going to have to go outside and play hard with him and wear him out before he comes in to bed. Give him a good chew toy or two that he only gets when he's in your room at night.
Be very sure that you take responsibility for him, feed him, groom him, start teaching him obedience, so that your Mom can't say that she has to take care of him. Plus, if she sees that you are being responsible, she may decide that you are learning a lot from having Neko and realize that he's a good thing in your life.
And hey, compared to my dogs, Neko IS a little dog!