My CIP was Bazaar Café in which I worked as a volunteer in a café primarily washing dishes. It was almost always a good way to practice my Japanese and talk with locals.
When the café got busy, the CIP became extremely tedious and boring as everyone would be busy working and I would be busy washing dishes. However, when the café was not busy, people would converse and sometimes even feed me.
My advice is make sure you know your goals before choosing your CIP. Understand what you want to get out of your CIP, such as improving language skills, learning a new skill other than Japanese language, and/or surrounding yourself with locals, before picking an activity. Also, do not be afraid to come up with something on your own and do the research to facilitate it.