As you move into your new house your little sister is upset you can no longer sleep in the same room now that your older and need privacy. She wishes she had an older sister instead so the spirit of the new house grants her wish. As you dream away the spirit in the form of a child invades your dream and turns you into a busty older sister both in your dreams and real life.
"It's so unfair! Without you in my room protecting me at night, I'll be completely vulnerable to the dark" your little sister protests.
"Well then buy a night light." You respond." we can't sleep in the same room anymore, it's weird. I'm a guy I need my privacy now"
"Well I wish I had an older sister then" she cried running to her lonely room