South Korea and Japan in 24 days

Hi, I have 25 days off work in April and have decided to pick up my bags and go somewhere different.

I currently have 3 options in mind:

Option 1: South Korea and Japan
Option 2: India and Nepal
Option 3: Central America

Could anyone in this forum give me a few thoughts as to whether this is feasible and if so a recommended itinerary. I like most things; nature, cities, beaches etc etc. and want to combine a bit of everything into my trip. I'm a 32 lone female and will be backpacking, although happy to spend a few extra pounds so i'm starying in somewhere fairly decent...my standards have tended to go up over the years...having said that i've just left the army, so happy to rough it if/when necessary.

Any thoughts on places to go and see would be appreciated. Also top tips from getting to Japan via ferry as that is the current plan.

Thanks to all that are able to reply!

Jude

P.s. similar post placed on the other Asis and Central America forums for Options 2 & 3