How to Make It
Puree the cherries in a food processor. Pass the puree through a fine strainer set over a small saucepan, pressing on the solids; you should have 1/2 cup of juice. Stir in the sugar and bring to a simmer over moderate heat, stirring to dissolve the sugar. Transfer to a small bowl and refrigerate until chilled, about 15 minutes.
In a large pitcher, combine the sweetened cherry juice with the yuzu juice. Slowly pour in the Champagne. Serve the Bellinis over ice.