Sweet bun filled with red bean paste (an). アンパン。A type of kashi-pan, sweet buns or buns with sweet fillings ("kashi" means "confectionery").
The original sweet Japanese bread, invented in 1875 by Kimura Yasubei, a samurai turned baker. The bakery, Kimuraya at the Ginza, still flourishes. Bread was considered as too sour for Japanese tastes, moreover rice was still going strong as staple food, so there was little space for a meal of ordinary bread on the Japanese menu.
Mr Kimura therefore decided to sell bread as a snack. As a filling he used sweet azuki-bean paste (an), after the analogy of manju buns. It became a great success and anpan is still popular. Kimuraya also makes other types of anpan, for example with the addition of sesame seed, or chestnuts. In the 1960s anpan became extra famous thanks to the manga Anpanman, about a hero with a head consisting of an anpan bun.
Filling bread with beans seems a strange idea, until you think about the British who eat white beans in tomato sauce on toast... The anpan bun on the photo was so richly filled with bean paste, that it formed almost a full meal...