Where can I look for the gear Kiyomi Otaka uses?

Find and submit the pianos, keyboards, synths, microphones, and other instruments used by Kiyomi Otaka.

If the artist is active on social media, check places like their Instagram feed and look for musical equipment they can be seen using.

You should also do a Google image search for things like "Kiyomi Otaka studio" and "Kiyomi Otaka live" and spot gear that way.