Osaka <> Tokyo + KIX JR Pass worth it?

Hi there!

Yes, if you do a return to Tokyo from Osaka any further travel, including your travel to KIX will be free. Here's a breakdown of your ticket costs for comparison with a 7 day JR Pass (¥28,300):

1. Osaka > Tokyo: ¥13750, (194mins, 556km)
2. Tokyo > Osaka: ¥13750, (194mins, 556km)
3. Osaka > Kansai airport: ¥3140, (57mins, 64km)

TOTAL: ¥30640 for 3 legs

As you can see you'll make minimum savings of ¥2340 with a 7 day rail pass. In addition to this, all further JR travel will be free, including all the JR lines in Tokyo (here's map of JR lines in Tokyo for reference), or day trips out of Osaka using JR lines, for example Kyoto, Nara, Himeji and Hiroshima. :)

Hope this helps!