I second-rec
Arashi-yama in Kyoto, not particularly the Monkey park, but the place in general. It's very beautiful and they sell awesome food over there.
Tokyo > Ikebukuro > TENGU which is a restaurant, located near that famous 'park' (Ikebukuro West Gate Park, anyone?) it's somewhere on the nth level of a building, but the food is awesome and the people were really friendly over there.
Nabari > Akame waterfalls which might be a little out of the way for people not in Nabari, but it's really worth the look. It's basically a long hike through a forest/mountain area with 48 waterfalls, varying in shape and size.
Nikkou > National Park which is very, very popular amongst tourists, but not solely without reason. next to the the park is the Shinkyou, or the 'bridge of the gods', and in the park itself you can find the mausoleum of Tokugawa Ieyasu, amongst a lot of other amazing temples and shrines and general things-to-see.
Nagoya > Port of Nagoya Aquarium is an amazingly big aquarium with dolphins and all sorts of freaky sea creatures from across the globe. It's located near the harbor port, so there is lots of amazing sea & water-related stuff you can see and do over there. The food in the restaurants in the mall connected to it is very delicious as it is mostly fresh seafood
(weirdly enough, near the parking lot of this aquarium you can see the remains of what once was an Italian Theme Park.... XD)