Xi Shi Red Pomelo

Freshly picked grapefruit needs to be placed in a cool and ventilated place for a week before it becomes sweeter. This is because the grapefruit will respire during this time, and the respiration of the fruit will accumulate sugar, so it will taste sweeter.
But be careful not to store it for more than a month. If stored for too long, the grapefruit will become shriveled because of excessive water loss.

Bigger than a grapefruit. Actually, pomelos are the biggest citrus, originating in southeast Asia. Peel or cut the thick rind to get to the sweetness inside. It won't let you down.