The PRC response has finally come through over the last 24 hours. But it has been unsatisfying and shaky, ranging from surprise, to righteous condemnation of Japan’s motives, declaring the incident to be an “absolute fabrication,” now to arguing that the MSDF was silly enough to mistake a surveillance/early warning radar for a fire control radar (that would be indeed be silly, since the Yudachi engaged in evasive manoeuvres to escape the Chinese frigate!)
The Japanese have dug their feet in first by saying that the Chinese response is simply not good enough and for them to go away and think about it more carefully. Then Minister of Defense Onodera has come out and suggested (日) that there was certainly no mistake and that they have video, photographic, and if needed, electronic evidence of the supposed infraction. Onodera argues that, a “normal” radar “spins” while it is monitoring while a fire-control radar continuously tracks the “target” as it moves. 「通常のレーダーはくるくる回って警戒監視をするが、火器管制レーダーはその（目標の）方向に向けてずっと追いかける」
He also said that in addition to the confirmation of this through visual imagery, they have electronic records as well which were carefully analysed by an expert at Yokosuka Naval Base on return. Onodera emphasised that a fire-control radar is a specialized radar that emits a type of electromagnetic wave with a distinctive wave frequency. 「電波を発する機械で、しかも（周波数などが）特殊なレーダーだ。それもしっかり記録しており、証拠として間違いない」
That said, the Japanese government is still considering releasing these records due to it possibly revealing sensitive national security information. It is understood that some in the MOD are not too keen to reveal more than images.
On the bright side, a number of Japanese news agencies have all noticed that PRC incursions around the Senkaku Islands themselves have reduced since the Japanese made their accusations. It will be interesting to see if they double down on the various broad accusations they have made, or whether they will approach the Japanese for a face-saving way out of the issue (for a price perhaps?)1. Or simply ignore it? (the “pfffft….whatever” strategy that the PRC uses when things are really tricky)
Jun Okumura has also been putting up more timely analysis regarding the latest radar incident.
Kyle Mizokami has an interesting thought experiment up at JSW regarding what could have happened between the two vessels involved in the incident militarily, if you are that way inclined.
1 This price could be an agreement along the lines of an agreement not to do such things again in the future such as I mentioned Japan and Russia have agreed to (a tacit admission that that is what happened and removes that particular tactic from the PRC toolbox). Or the implementation of a maritime “hotline” mechanism which has been mooted over the last few years and was apparently making progress towards implementation before the Senkaku controversy erupted late last year. The PRC ambassador in Japan two days ago recognized (日) the need for such a mechanism. The one risk for the PRC with such a hotline is that if it is called upon it may reveal weaknesses and irregularities in terms of the political and military chain of command, a consideration very relevant if we assume that this recent incident is a PLA-level rather than Xi Jinping-level instigated incident. Okumura above even suggests that a dialing down, but not elimination, of Chinese government patrol boats entering into Senkaku waters may be possible, thereby killing two birds with one stone.