There are two type of breakfast pattern at home in Japan, it's rice or bread. I am in the bread group and eat Japanese Pain de mie "Shoku pan" for breakfast. "Shoku pan" has usually square shape, it's the most plain bread used for toast and sandwich. It's such popular breakfast for Japanese, like this post "16 Cliched Problems Only Anime Characters Will Understand" says, you see character eat shoku pan while running to school often in manga. Since bread grope eat it everyday, shoku pan is very reasonable, one pack costs 100 -120yen. But recently we have rich shoku pan boom. 7/11 Japan sell "Kin no Shokupan" (golden shoku pan), it costs 250yen because they use better flours and better butter, but they sell over 7.2million of packs already, after that, other convenient stores started to sell expensive sandwiches and they all make good sales. In June finally rich shoku pan shop "centre the bakery" opened in Ginza, they sell only shoku pan and sandwiches. They have interesting system, if you choose a toast, you need to choose the toaster first and take it to your table, then choose bread, butter or jam and make toast by yourself. I wanna try this.
By the way, Japanese bread tend to puffy and sweet, I personally like hard non sweet bread like German bread, it's hard to find such hard bread though. Foreign people's opinions are divided very much for Japanese bread. These are well known videos introduced in Yahoo Japan.