Well, with the current plans, the JMSDF is going to have the following number of very decent, modern DDGs
9 x Murasami
5 x Takanami
4 x Akizuki
2 x Asahi
4 x Kongo
4 x Atago
In my opinion, the Kongo, Atago, and Akizuki are all either AEGIS or AEGIS-like vessels...making a total of 12.
The JMSDF is not as large as the PLA now, or in the future...but they are very ship shape and capable, and allied with the US, Australia, and Koreans, they make for a very powerful offset to the rising PLAN force.
If you take the AEGIS capability those four navies have in the Pacific, you end up with something like 50 AEGIS DDGs, plus however many AEGIS cruisers the US Navy keeps in the Pacific.
That's 28 very decent DDGs. They will also be building new, more modern FFG sized vessels soon.
On top of that, with the 4 x Hyuga and Izumo and the 3 x Osumi, they have a decent flattop fleet for ASW and Air Assault, and then of course the ultimate 13 x Soryu and 9 x Oyashio subs (that's 22 large SSks that are very capable vessels).
You add the Korean and Australian SSKs, and then the US Navy SSNs, and this underwater threat is perhaps the most dangerous threat the PLAN faces.