Hi there,
For a 14 day rail pass to be worth it you need to spend over ¥45,100 on individual tickets. Lets take a look at your costs:
- Warabi > Osaka: ¥14160, (240mins, 576km)
- Osaka > Kyoto: ¥540, (29mins, 42km)
- Kyoto > Nagoya: ¥5640, (49mins, 147km)
- Nagoya > Yokohama: ¥10150, (107mins, 345km)
- Yokohama > Warabi: ¥780, (61mins, 48km)
TOTAL: ¥31270 for 5 legs
As you can see, it will be cheaper to purchase individual tickets for this trip than buy a 14 day rail pass if your itinerary cannot be changed. As an alternative, if you can manage to fit your travel into 7 days, a 7 day rail pass (¥28,300) will give you a saving of ¥2970.
The Japan Rail Pass is useful for in city commuting if you are using JR lines. Osaka, Yokohama and Tokyo have a good network of JR lines and can be very accessible depending on your plans. However, Nagoya and Kyoto run mainly using the internal metropolitan metro system, which is not free for JR Pass holders.
Hope this helps!