Greenery in the Park
The park is green, the park is radiant, the park is fun.
A side trip to the local park can be a good change of pace from the busy city life. Best of all, bigger parks may have more to offer than simple smaller ones. The one I went to even had a cafe and mini museum of sorts. Definitely research such places if you are looking for an alternative to stuff to do in an urban setting.
If you happen to be a foreigner who is looking to meet Japanese women or Japanese singles then please check out EXEO International. Speed dating events are offered weekly.