CD-ROM with Lana online software (which appears to be some sort of NIFTY-Serve (CompuServe)-based online community software), karaoke software, and Faith serial driver, compatible with both DOS/V and NEC PC-98:

The CD-ROM has by now been unsealed, so I could have a look at the included booklet. 😀

Casio-branded 9V power supply (100V input for Japan):

Serial cable with adapter:

Casio-branded DM-5 microphone:

The mike feels quite solid. Don't know yet how it is sound-wise.

Left speaker with nice gaudy sticker on the front and connection cable on the rear:

Right speaker with integrated General MIDI sound module, microphone amplifier, and hardware echo function:

The "speaker" connector is for the left speaker. It also has a separate line-in.

Bottom copyright with serial number:

I find it interesting that it was specifically made by Casio Computers instead of their music division...

Paperwork:

Everything is in Japanese only. Half of the paperwork is for the Lana Online software, the other half for the GZ-70SP proper. Connections quick start guide:

The Manual is almost entirely in Japanese, except for the instrument lists.

Specifications:

General MIDI instrument lists:

General MIDI drum sets, including Roland TR-808 drum set:

MIDI chart:

I don't know how it sounds yet, although IIRC there's a demo on Youtube.

From my searches, the 70SP has the same MIDI hardware as the GZ-30M. So sound wise, it is a step below the GZ-50M. I have become quite fond of my GZ-50M, and am hoping to get the 30M at some point, just because it is so tiny and cute. 😀

Hey, can you please donate that product to me so I can make MIDI conversions/comparisons with that?
My address is: REMOVED
Please send the GZ-70SP to my address. You better do this now or else I won't make more MIDI comparisons!

EDIT/mod comment: Address removed. Not wise to publish your home address in public on the internet. You may never know when it will used against you.

Apparently it also exists in a very nice metallic blue finishing (picture stolen from Y! Auctions Japan):

Man I would love a pair of these. Any good midi recordings?

Haaa, finally tested these with a MIDI keyboard. The sound set is rather uneven: nearly all synth pads are quite good, some excellent, part of the strings are great, while any blown instrument sounds highly unrealistic at best and pretty crappy at worst. The percussion is good to great, but the pianos, chromatic instruments, and anything else with keys are rather boring. The string instruments that aren't great aren't great because they sound like keyed instruments. There's something weird going on with the sustain part of the envelope on patches with long sustain, likely looped samples (in some cases you can hear the tail end of the attack for a bit when the sample loops).

There aren't many options to modify the sound: modulation, pitch bend, main volume, pan, expression, sustain pedal, sostenuto, soft pedal, most available via CC. There seem to be some more options available via (N)RPN messages, but the instructions for that are almost entirely in Japanese without sysex codes.

The microphone volume needs to be turned up quite far to hear anything, and I cannot get the digital echo to work.

Okay, I guess this one will need some work: The microphone circuitry falls silent now and then, and the problem with the digital echo appears to be that although the op-amp connected to the digital echo level pot works the digital echo effect is not produced.