@Monochome_Scholar They usually use a type of toasted bread with liberal amounts of sugar incorporated in the baking to make it very sweet. Either way its nowadays a type of fluffy white bread that you rarely see ouside of Japan whether its got sugar or not. Its quite light but voluminous. They glaze and drench it in honey and other syrups too, hence the name.
Youre also not necessarily eating the whole thing yourself. The insides are usually cut up into cubes or other sections them put back into the crust with other savoury or sweet fillings. Its easy to share....like say between couples.