This classic-looking sixties combo organ was part of a whole range of Ace Tone organs (Ace Tone Corporation’s main product line), most of them still very much in demand even today. The model 9 was one of the high-end models available in the TOP series, with a wide variety of voices, a good-sounding vibrato, reverb/sustain on two voices, split keyboard for bass, bright tabs, staccato mode for the bass section, and also an optional bass pedal board. All of this with classic red tolex, chrome legs, rocker tabs and gray/white keys for the bass section.
This is as far as I know the only monosynth ever produced by Ace Tone, although there were many other keyboards, including a string synth (the Multistring SY-5) and lots of combo organs, such as the Top-9. This instrument was most probably designed at the tail end of Ikutaro Kakehashi’s tenure at Ace Tone before founding the Roland Corporation, since many of its design features can be found on Roland gear of the era.