http://www.jal.co.jp/en/inter/lounge/member/class.html
It says, TPE passenger have access to the Sakura lounge.
AFAIK, JAL operates 9 lounges there :First class lounge / Sakura lounge / Sakura lounge Annex / JGC lounge / Family service lounge in the main terminal-2. 3 more lounges(First & JGC & Sakura) in the satellite terminal, plus one Sakura lounge in the domestic terminal....but none of them has equipped with shower.
Check this out! (NRT official web-site)
http://www.narita-airport.jp/en/guid...svc_37_t2.html
I bet you can afford 500JPY