Japan Airlines musical instruments: choose a case, checked baggage, or an extra seat

What this answer depends on

• Violin loaner case: on eligible JAL Group domestic flights operated by aircraft with at least 100 seats, a limited number of loaner cases can carry a full-size 4/4 violin and bows in the cabin. Availability is listed at Haneda, Narita, Itami, Kansai, New Chitose, Chubu, Fukuoka, and Naha. The case cannot be reserved: ask a counter representative at the departure airport on the day of travel. Transfer the violin and bows yourself; the loaner goes in the overhead compartment and your personal case is checked. This loaner service is not available on codeshares. Because stock is limited, arrange a backup rather than relying on availability.
• Other loaner cases: JAL lists protective containers for guitars and small instruments at airports served by JAL Group domestic flights; they cannot be carried in the cabin. Ask a counter representative at the departure airport on the day of travel; these cases cannot be reserved in advance.
• A large case for a double bass or bass fiddle is also for the hold, not the cabin. Reserve it through JAL's Domestic Contact Center at least 48 hours before departure, and reach the baggage counter at least 60 minutes before departure. JAL lists the large-case service at airports served by JAL/JTA domestic flights, excluding RAC, JAC, HAC, and J-AIR flights. Its listed inner dimensions are 58 cm at the top, 87 cm at the bottom, 201 cm deep, and 75 cm wide.
• When an instrument exceeds the ordinary carry-on size limit and you arrange an extra seat, JAL permits securing multiple smaller instruments such as violins or violas in that seat when their combined width is 43 cm or less. Contact JAL's Domestic Contact Center to reserve.