This is a good blowfish restaurant, which isn't known to the public.
This Izakaya restaurant is called Kagaya and this is one of the best holes in the wall in Tokyo.
Ever since then I’ve never wanted to have that kind of experience again, or to cause trouble for others, so I’ve stopped going to the little-known place where you can fish for fugu.
A hole place is what's known as a hole in the wall. This is a place that looks small, hidden and dingy, but probably has awesome food.
The readings are the readings you learned with the kanji.