Ferries - Any booking required?

Hello!

My trip to Japan is going to start soon and I would like to ask a question about ferries. I'm planning to take two ferry rides during my stay; first from Yokohama to Tokushima, and later from Yawatahama to Usuki.

Now, should/could I do some kind of reservation or can I just show up there and buy the ticket? Is there anything that a person who rides a ferry the first time should know?

Thank you!

1)
No operate from/to Yokohama port.
Back to Tokyo "Ariake" port first by trains and bus(or taxi).
http://www.otf.jp/terminal/tokyo/
http://www.otf.jp/reservation/ (booking)

2)
http://www.94ferry.co.jp/kuseki/ (booking)

Both Ferry web online booking possibe but no eng menu and inputs.
Call to reservation center [予約(yoyaku)センター(center)].

Use google translate.

BTW,why by ferry to Tokushima?
http://www.topia.ne.jp/english/tourism/access.html