There isn’t much info going around on the Japanese Mirano company: apart from a line of tape delays, a fuzz pedal and a booster pedal, I couldn’t locate anything else online. For reasons I ignore, I do know that they later became the Hawk Corporation, who produced a few more delay units such as the amazing HE-2250.
No doubt one of the most sought-after features of the Mirano 3 is its tube circuitry, which in itself makes it appealing. Using an electric guitar plugged directly in the unit made it warmer and fuller sounding, although I couldn’t overdrive my guitar through it, even with the Mirano and guitar volumes at maximum. The delayed signal can be overdriven easily, but not the dry signal, so I guess you would need a signal boost at the input to do so, at the expense of a clean delay. Nevertheless, I’ve used it as a clean preamp on occasion.