ISO FRESH Mochi Ice Cream...
Are you referring to Yukimi Daifuku, ice cream wrapped in gyuhi?
)Mochi and ice cream wouldn't go together well, because mochi is eaten hot. If you chill mochi, it will harden and become inedible.
If you mean Yukimi Daifuku, I don't think you will find a restaurant that serves it.
It's junk food and I think restaurants would not consider them a valid dessert (like you won't get Freezies as a dessert) , and secondly wagashi, or Japanese sweets, are usually offered separately as a teatime snack and does not make part of a meal, or, should I say, most Japanese style meals do not have the concept of serving desserts to begin with (with a few exceptions of course, e.g. kaiseki).
In Japan, if you want to buy/eat wagashi (non-supermarket quality) you would go to a wagashi store (Japanese version of a Western patisserie) or a kanmi-dokoro ("sweets shop" that serves tea and wagashi).
If you want fresh stuff made, you can always make your own. Not hard at all:)