Katsu sando ice is a joke that took itself seriously enough to become a real product. It is not a sandwich. It is an ice cream novelty that either tastes faintly of the flavors that suggest a cutlet sandwich or, more often, is moulded and decorated to look like one: a slab of ice cream cut and dressed so it reads as a fried cutlet between two pieces of bread, complete with a piped stripe standing in for tonkatsu sauce. It lives in the catalog as a curiosity, the point at which Japan's affection for the katsu sando loops back on itself and turns the sandwich into dessert. Treating it as anything other than a deliberate novelty would miss what it is doing.
The craft, such as it is, is confectionery sculpture and visual punning rather than cooking. The "bread" is usually a pale sponge, a wafer, or a shaped block of vanilla or milk ice cream, squared off to mimic crustless shokupan. The "cutlet" is a contrasting layer, often a denser or differently colored ice cream or a textured insert, sometimes dusted or coated to fake the look of a coarse panko crust. The "sauce" is a dark caramel, chocolate, or fruit ribbon piped along the edge to land the visual gag. The whole thing is then cut on the diagonal and stood up so the cross section shows the fake layered structure, because the entire payoff is in that reveal. A good one commits to the bit: the proportions read instantly as a cutlet sandwich, the cross section is clean, and it actually tastes like a competent dessert underneath the costume. A weak one is a melting blur where the layers smear together and the joke collapses before anyone can see it, or a frozen brick that is all gimmick and no flavor, novelty doing the work that the eating should.
The variations are whatever a given maker decides to riff on: a flavor-led version that leans into a sweet-savory caramel-and-cream profile, a purely sculptural version that is just nicely made ice cream in disguise, and seasonal or collaboration one-offs built for a photograph more than a craving. The real fried katsu sando it parodies is an entirely different and serious thing, and that one deserves its own article rather than being crowded in here.