It's definitely blended, or at least blackcarded. There's no such scene.
However! One thing I know about Japanese fireworks is that they don't spam like Singapore and instead shoot just up to 3 at the same time or so, space it out in terms of time, and also space it out literally, shooting over a different part of the sky throughout the entire show. I experienced that in Mt Fuji. Some were shot high, some were low. Over 10secs, only 3 fireworks were shot, not like Singapore where they spam and everything goes white due to overexposure or smoke. By spacing it out, smoke doesn't affect the fireworks so much, and allows you to capture individual fireworks nicely. So blending into such a scene is much easier without worries of smoke and overexposure due to spammage.
It's almost like the Japanese choreographers did it for photographers!