My Miku day submission is the NSX-39 ("NSX-miku"), a MIDI stylophone that also happens to be a shockingly fully-featured vocaloid synthesizer.
The stylophone part is very easy to understand -- there's a stylus you remove from the bottom of the device, and touching it with a key makes it make a note. Comes out of the speaker, and you'll either get a basic vocalization (what the A-E-I-O-U keys or for) or a poem (if you hit shift + one of those keys; shift+U is the iroha for example). That's the simple operation, but you can also use it as a MIDI output device and that's where this thing's more impressive nature as a hardware vocaloid device really shines through.
I didn't think much of this when I bought it -- I just wanted a fun little toy to experiment with melodic ideas on. In fact I've ranted before about a dislike of MIDI modules on here before (see my anti-hardware club rant about the MT-32) and how annoying they are to integrate into a computer audio setup, but, while I haven't used this much...I think I love it?
In MIDI output mode, it's able to be a full MIDI output device. It has a full set of MIDI synthesizer voices, with the one distinction being that channel 1 is Miku Mode. There's a lot of documentation about the things you can do in this context, but if you're like me you can just load up Anvil Studio, set the NSX-39 as the output device, and suddenly you have your midi audio, which you can listen to with the headphone out (weirdly, there's no line-level out on this device, which is the one thing that would make this a surprisingly impressive potential piece of kit). The back of the manual has info on what the SysEx messages are in MIDI mode to set the vocalization, which includes every syllable in Japanese -- so it's entirely possible to create songs with proper lyrics using this thing.
Considering what the vocaloid software goes for, I'm astounded at how dang cheap this thing was. It's named the way it is because it's based on the NSX-1 eVocaloid hardware (and if you're familiar with that, it has a fallback mode that can be used in the same way, but I haven't had any need to mess around with that so far).
There are a ton of web resources about programming this thing, too, some of which can be saved to the device firmware, but that's a lot of info to cover over the short period of time I've had this, so I will probably need a while of messing with this thing before I can speak about any of that with any kind of authority.
I was hoping to use this thing during the compost -- which I probably won't have enough fully-uninterrupted time to work on until this afternoon, so you'll have to wait for that -- but I'm not entirely certain how to square away Miku's vocal aesthetic with "goblin", so I might have to do something else instead.
