Really love this drama after watching 2, so when back to watch the first one.  The cast is great (good looking and fairly decent acting) and the story line is very interesting.  

I actually really like the simple and easy to understand diagram explaining the operation.  Really not sure how real and close to real are those info.  But it really help you to understand and follow the story with that bit explanation.

This is indeed a very successful series I am hoping there will be Iryu 3 coming out in the future

Check here for a terser clip.

More background info from: