How directed-energy weapons could fit into a destroyer's defences

How many directed-energy weapons would you fit on a modern Japanese destroyer?

Possibly four, or three in a different arrangement, alongside other defensive systems; the recommendation depends on the technology becoming reliable enough.

Four directed-energy weapons are suggested as a possible fit for a modern Japanese destroyer. A follow-up recalls an earlier three-mount arrangement, prompting clarification that the number depends on the other defensive systems carried. The proposal is for several complementary systems, with three or four mounts of each where appropriate. It remains conditional: the available directed-energy systems are not regarded here as proven enough to rely on for protection.