Maybe you should be on your own rather than with your friend during the second half of your trip. Decide what you want to do. Do you like museums? Do you like cultural things; art, play, music, etc.? Do you like outdoor; ocean, mountain, or may be stroll at park? Do you want to do a day trip or stay in Tokyo? Do you like food? Nothing wrong with going for meal by yourself.
Once you come up with those basic answers, then ask people at hotel for recommendation. Hope you will enjoy rest of your stay at Tokyo. There are a lot to do and see around Tokyo.