A few cities – including Tokyo, Osaka, Kōbe and Sapporo – have cycle-share schemes. They can be a little tricky to use, usually requiring advance registration online; follow the online directions. Many Japanese use bicycles to get around cities; by law bicycles should be ridden on the road but many people use the pavements. Cycle lanes are pretty much nonexistent. Drivers (and pedestrians) are generally courteous. In cities, bicycles should be parked at ports or designated bicycle parking areas.
Many tourist areas have bicycles for hire. These are almost always heavy-framed, single-speed shopping bikes, though some places have electric bicycles; child-sized bicycles are rarely available. They may be free as part of a local tourism initiative; otherwise private businesses, usually in the vicinity of train stations, rent them out for about ¥1000 per day. Ask at the local tourist information centre. Many youth hostels also have bicycles to rent or borrow.
Helmets are mandatory for children 12 years and under. Unless road touring, adults rarely wear them so rental shops don't provide them (unless they offer children's bicycles; then helmets for children will be included in the rental).
It is difficult to rent touring cycles in Japan; Cycle Osaka is one operator that offers them. To take a bicycle on a train, it needs to be broken down and stored in a bike bag.