Yakushima jetfoil - need reservations?

Hi there, we're planning a two week trip to Japan at the beginning of March. We've booked most accommodation and car hire etc, but the trip hinges on getting the jetfoil to Yakushima (and back again) on two specific dates. Do you need to reserve these in advance?

Whilst we know the date we need to be in Yakushima, we don't necessarily know what time we'll arrive in Kagoshima in order to get the jetfoil. So really we just want to rock up and get on the next departure. Is that likely/possible, or should I attempt to reserve ahead? It shouldn't be necessary for weekdays in March, right?

Thanks for your help!

If the jetfoil is not full, then you can buy a ticket right before departure at the jetfoil terminal.

Reservations are possible in Japanese online:
http://www.tykousoku.jp/

Or by phone: 099-226-0128 (probably Japanese only)

It's not high season then, so you should be fine!
The problem with the jetfoils is that they easily get cancelled if the waves are too strong - which happens quite often in Yakushima. The big ferries take longer, but won't be cancelled that easily.