From japanesefood.about.com. I have not yet tried this recipe, so my comments are largely based on others' comments and on my own experience with Japanese bakery cakes. This is a popular cake in Japan at Christmastime, but it is delicious any time fresh fruit is in season! I like strawberries the best, but peaches and mangos are also nice. Use any fruit or combination of fruits you like. Chop whatever quantity of fresh fruit you'd like for the filling (halved or sliced strawberries are particularly lovely set into the whipped cream), and save some to decorate the top with. Be sure to whisk the eggs very well to make a nice, light sponge. There is no leavening added in the original recipe, so the height and texture are all due to having well-beaten eggs. Some reviewers of this recipe who had trouble getting it to come out right added some baking soda, and some also added a little vanilla. The cake should be eggy, not vanilla-y, but feel free to add the vanilla if you prefer. Both of these will be listed as optional ingredients. The prep time is estimated.