That's wonderful if you are going to kita Osaka or downtown Kyoto.
But not if you are going to Sakai,

For Sakai, take Nankai's express instead of JR. No exchange needed.
For Uji, take Haruka and change trains at Kyoto.

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(Mr.) IIJIMA Hiromitsu,
aka Delmonta http://www.ht.sakura.ne.jp/~delmonta/