One of the biggest headaches for those cycling around Awaji Island is how to transfer themselves and their bike to Shikoku Island.
Recently,Awaji Kotsu (Awaji Public Transportation) announced their new service, delivering cyclist’s bicycles by their bus service. Until now, they have only provided the service on a short term or test basis. Please find the details below regarding the new service.
Since cycling across the Onaruto bridge, is prohibited, cyclists with no Japanese are often restricted to pre-arranged, private transfers.

JPN article for new bike transfer service by bus

1. Transfer by public Bus from Awaji to Shikoku:

The Awaji Kotsu bus, operating between MInami Awaji-shima IC (Awaji Island side Bus stop) and ShoNaruto (Shikoku-island side Bus stop) recently adopt Bicycle fixing gear at the luggage compartment, bottom part of the bus.

How to Load your bike into the bus compartment

As you see, Page 1, the fixing gear can be drawn by the bus driver.
You can release front wheel and fix with the gear by quick release.
Also, they have another compartment to put bicycle packed in bicycle bag (page 2) .
Maximum loading number for bike rack is 3, for bike back case is 4sets. And required booking detail

You will find the guide at route #25

Sorry but they have NO English explanation guide.
Time schedule is as follows
Depart from Minami Awaji IC Bus stop: 08:55, 12:00 and 16:30
Depart from Onaruto Bus stop: 09:19, 11:19, 14:34 and 19:04
WEEKEND and Holiday:
Depart from Minami Awaji IC Bus stop: 7:35, 12:00 and 16:30
Depart from Onaruto Bus stop: 09:44, 14:19 and 19:04.

Bus Stop at Awaji Side (googlemap)

Bus Stop at Awaji side

Incase of bike loading (both bike and bike bag), prior booking required.
TEL: 0799-22-0808 (09:00 to 17:00) Prior booking accept from 1 month before till the day before of each departure.
The Bus fee is 660 yen, no extra charge required for bringing a bike on board.
Please note loading/unloading bike is only admitted at the above two bus stops. You cannot drop/put your bike at other bus stops.   Currently they do not provide an English version.
The bus stop at Minami Awaji-shima IC (Awaji Side)

Bus Stop at Shikoku side

Bus Stop at Shikoku side

2. Future plans for Linking Awaji/Naruto

Onaruto Bridge – Passageway for cycling on the bridge:

Hyogo prefecture announced their new project proposal to add a new passageway underneath the current road for vehicles
The Onaruto bridge, 1629m long between Awaji Island and Shikoku Island, currently used for highway traffic only has double decker construction with the upper side currently used for cars, underneath was designed to be used for trains.  At this moment this section remains only as a framework. If the proposed plan by Hyogo prefecture goes ahead, the underside passageway will be modified to allow bicycles.

Although this plan hasn’t been put into action as of yet, we hope that the recent surge in popularity for cycling will have this plan come to fruition sooner rather than later.

The article for the above bike passage project