Much more to this longish article at the JUMP:
The Day When Japan Has A True Aircraft Carrier 21 Aug 2013 Hiraku Katsuyama
(SEKAI NO KANSEN (JAPAN) 01 SEP 13) Hiraku Katsuyama is former admiral and Japan Maritime Self-Defense fleet commander.
"...Possibilities for the 22DDH Light Aircraft Carrier
It is still assuming a lot that Japan will acquire a fifth-generation V/STOL fighter plane (from here, generally understood to mean the F-35B), but I will discuss the developmental possibilities for the 22DDH helicopter carrier with this assumption.
1. Putting the F-35B Into Operation Without Remodeling [the 22DDH]
The 22DDH would be able to serve as a takeoff and landing, as well as a holding, vessel for the F-35B. As for the number of planes, in addition to pilot rescue helicopters and a V/STOL AEW aircraft, and considering the placement of the aircraft moorings and the necessary work space, it is thought a 22DDH could hold ten or so F-35Bs.
The problem is the payload for the planes on board. In the case of aircraft operations with the 22DDH, compared with a large aircraft carrier or a light aircraft carrier equipped with a ski jump ramp and landing equipment (arresting gear), the 22DDH would be fairly constrained as far as its combat radius and the number of missiles it could carry. However, since these constraints could be mitigated by advancing close to the area of operations so that the planes could be utilized, even though the number of planes would be limited, if a high-performance fifth-generation fighter plane like the F-35B is part of the equation, the 22DDH could play a substantial and active role.
2. Equipping a Ski Jump Ramp
A 22DDH could be equipped with a simple-type ski jump ramp. One way would be to attach a truss-structure ski jump ramp near the bow of the vessel. Even though this would include reinforcing the ship’s hull, attaching a ramp would require relatively little construction work, time, and cost.
However, in this case, to ensure an adequate length of the runway for takeoffs, the standby area for the next plane to takeoff will have to be limited, which would lengthen the intervals between takeoffs. Moreover, since a ski jump at the ship’s bow will create air turbulence, the direction the vessel can take during landings will be constrained.
A truss-type ski jump ramp would be made on land in advance, requiring several months for the construction and attachment and costing under 100 million yen. (The construction period and costs are estimates taking into consideration the relationship with the ship’s hull; further research needs to be done on matters, such as the adding of ballast, related to maintaining the ship’s performance. The same holds for the option described below.)
One other option is to build a full-fledged ski jump ramp within the bow. In this case, the 22DDH would be able to carry out flight operations as a light aircraft carrier....
...even if the 22DDH is commissioned into service in line with the current plan, it could still serve as a takeoff and landing and holding vessel for V/STOL fighter aircraft. In order for Japan to prepare itself to be able to deter and prevent independently attacks on the Nansei Islands, particularly the Senkaku, Miyako, and Yaeyama islands, adding the F-35B operational capability to a 22DDH-class vessel is very meaningful. Moreover, it is also possible...."
The Day When Japan Has A True Aircraft Carrier - Association of Naval Aviation in Virginia Beach, Virginia - Hampton Roads Squadron