Depends on which person you are romancing. For Panki you can also be with Lel, Skylark, and/or Harmony. For anyone else it is a one-on-one relationship for now but the story is open to multiple-partner possibilities in the future.
Can you add a harem route in the next update?
Well it won't be the next update since that's a real big thing but there are plans for various harem routes.
