Should i buy 7 day or 14 days ?

This is my itinerary. wonder if I should buy JR Pass (7 day or 14 day) or other regional passes? Appreciate if you can help.

Arrived Osaka at morning
10 April - Osaka (stay at Osaka )
11 April - Osaka to Hiroshima
12-16 April - ( I'm going to Korea )
16 April - ( Depart from Korea to Osaka at 9:45 am )
17 April - Universal Studio Japan
18 April - Nagasaki ( return the same day )
19 April - Mount Fuji - Tokyo (Return the same day )
20 April - Osaka ( depart at 15:30 pm )

Thank you.