it appears to be a soundboard Acoustic pickup, that’s been modified for the Shamisen Skin with a regular TRS Jack, so while its a great idea if you want a Sound board piezo, another solution would be to find a way to mount sound board transducers onto the wood itself, but I wouldn’t recommend it.
If you want to play with pedals, either buy from the bachido store, or make a Koma, with a graphite saddle, and put a regular guitar piezo inside, or mod an existing Koma to hold a piezo, if you don’t plan on using an acoustic preamp pedal then you could look for an ordinary transducer from a well known acoustic guitar pickup maker, it should still play well with other pedals.
One thing I don’t recommend, unless you’re willing to do an excessive amount of modification, an Microphone pickup, I’m making mine from scratch.
there are few transducer piezo pickups, compared to under saddle piezo, that play well with preamps, unless either the preamp or transducer are compensated in the circuitry. Most companies don’t recommend it and few people had success, except with the preamp in the actual acoustic amp box.
In short your options are:
-transducer, pedals and amp only.
-“special” transducer that can work with preamps(few and rare, at least 75 USD or more, Shamisen-Katoh has an entire system, but I don’t think the sell the system separately, maybe LR Baggs, etc).
-under saddle piezo(if you plan on using a power jack/end pin preamp, or at preamp really)
-Microphone pickup(requires mounting inside the shamisen, some minor drilling, etc, but can also run with any onboard or signal chain preamp. Most acoustic sound, next to a transducer or blended system).
Note: preamps require batteries, 9v or recharable.