Japanese land based RDF was excellent. It's possible that that capability was instrumental in the loss of Amberjack, Grampus, and Triton during Adm Fife's early 43 "playing checkers with submarines" campaign, in which he required the boats to maintain more frequent radio contact than was the norm.
However Japanese shipborne RDF capability was not as good, certainly nowhere near the level of sophistication achieved by the Allies. My impression is that crews on IJN ships could fairly regularly intercept radio transmissions from nearby Allied subs, and make decently accurate assumptions about their proximity, but not bearing.
The Japanese had shipborne radar warning receivers; both metric- and centimetric-wavelength RWR's were operational by April 1944, and they slowly found their way into the fleet. Late 44 might be considered the date at which they were in fairly widespread use. Capabilities as follows:
E-27 (Kai-3) detected radar signals of 0.75-4.0 meters at ranges up to 300km using non-directional antennae mounted on each side of the bridge plus a "Racket" style antenna mounted on a rotatable pedestal to determine bearing of signal. 2500 units were delivered.
Model 3 (3 Gata) detected radar signals of 3-75 centimeters through a small directional bridge-mounted parabolic antenna. 200 units were delivered.
I don't have much operational data on the use of these devices within the IJN, and in particular, how many centimetric-wavelength RWR sets were installed, and by when. A fleet full of meter-wavelength RWRs in 1944 would have done them very little good.
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