Technically a 3000+ppm calcium JASO spec, diesel, in practice any good CI-4+/CJ-4/ACEA E4/E6/E9 will work well.
As suggested, Caltex Delo 400 15W-40, Fuchs Titan Ultralube 15w-40, ELF PV Plus 15W-40, Petronas Motolub CS3 15W-40, Shell Rimula R4, etc, but all in CI-4+ flavour.
If you can't find a CI-4+ oil, an API CH-4, ACEA E3/5 is fine, but the CI-4+ oils cope with soot better.
Don't use a CG-4 oil in a Japanese diesel, you may run into cam wear issues, particularly with high sulphur diesel, hence the 3000+ppm calcium specification.