Forgive my lack of information.
This will be an international flight (terminal 3) from DEL-NRT.
My Air India lounge search leads me to this link:
http://www.airindia.com/newsdetail.htm?481
However, I can only find information on the "Premier" lounge on the upper floors of terminal 3, and I can only find mention of pay shower locations following baggage claim of terminal 3.
the ai lounge in del is pretty decent, however i would not want to be stuck there for 9 hours....
as
oliver2002 suggested, it may be worth it to try the other lounges to see which one you like best....