A little outside central Sapporo, Hanke Sandwich & Inn is a lovely little sandwich shop just across the Toyohira River.
You'll need to cross the river to get here from the city centre, but why not make a nice walk out of it? The riverside is a great place for a stroll, especially when the weather's good.
The sandwiches here are properly good, especially if you like your bread with a bit of a crust and a decent bite to it.
One thing worth trying is their saba sandwich (grilled mackerel sandwich). You don't come across these very often in Sapporo, and it's a nice change from your usual sandwich fillings.
They take their coffee seriously too, so it's a great little spot to stop for a sandwich and a decent brew.
Nothing overly fancy, just good sandwiches, good coffee and an excuse to enjoy a walk along the river. Sometimes that's all you need.