7 day JRS pass

I plan to get 7 day JRS pass. Will my 7d JRS pass be valid throughout my trip if I will use the pass on May 12 (first day at about 9pm) to travel from Kansai to Osaka (and then use the pass afterwards throughout my travel across Kyoto, Nara, Tokyo) and finally use it on May 19 (last day at 10am) to travel back from Tokyo to Kansai ? If not, can you suggest other alternative that will save on costs ? Thanks

JR Pass is effective for consective calendar days. If you start using it on May 12, it expires on May 18.

Value ticket from KIX to Osaka
http://www.howto-osaka.com.e.iv.hp.transer.com/top/ticket/railway/

It is valid for 7 calendar days, so if you activate it on the 12th, it will expire at the end of 18th.

Since you are making a round trip between Osaka and Tokyo, it makes sense to buy the 7-day pass for that long-distance travel. But for the first night, from Kansai to Osaka, you "could" buy "Icoca & Haruka" package, or pay a single ticket for a Nankai train to Namba in Osaka, depending on where in Osaka you are staying.

Please check "How to travel between Osaka and Kansai Airport" on this page (please select "To/From Kansai Airport" at the top):

http://www.japan-guide.com/e/e4006.html

Or, if you want to go really budget, you could use overnight buses between Osaka and Tokyo, and pay for individual tickets (or prepaid card) elsewhere.

Thanks for the suggested site. so, it means that I'll just take another type of transpo to get to Osaka from Kix and use the JRS pass effectively on the following day so that I can use the pass en route to osaka from tokyo on the last day. is that right ?