[Coda]

メニュー -> オプション -> タイミング____ (I don't know the two kanji). You can fiddle with the slider and use the CHECK button to see if it synchronizes better, or you can use the SET TIMING button to have it give you a really simple note pattern and it'll figure out the latency based on how you play it. I used SET TIMING to get close and then fine-tuned it by nudging the slider and testing it until it was comfortable. (I wish I could set it to 0.135, because 0.125 is a little too early and 0.15 is a little too late, but 0.125 is closer and the timing windows are large enough that it's not really a problem. I've got Deemo set to 0.16 but I assume it has a bit more latency in its own code.)