Japan always been a place I've wanted to check out and lucky enough will be going there for a few days in June and wondering if anyone can recommend some cheapish accommodations in more lively areas. I am 21 so bound to want to party
You may want to check out the cheaper business hotels. There are some limitations on guests, but I've heard some good feedback of Sunroute hotels and there's one in Shinjuku.
If you plan to have guests at your room, be sure to check the hotel's policy on non-registered visitors.