Wash the yuzu well.
Thinly peel the yuzu.
Julienne the peels.
Squeeze the juice out. Weigh the juice.
Soak the peels in water for 4-5 hours (while changing the water occasionally.) Drain the water, and weigh the peels.
Pour enough water to cover the peels in a pot, and turn on the heat. Simmer until the peels soften (for about 15 minutes). When the peels soften, add yuzu juice, then add the sugar which is 60% weight of the juice + peels. Simmer until thickened.
Pour the jam into disinfected jars while it's still hot.