Dorami's Absolute Worst Day / The Best Melon Bread in the World

It's Dorami's birthday and Doraemon plans to buy melon bread from the famous melon bread shop as a birthday gift. As the sale of melon bread is only limited to four hundred, split evenly in four rounds, Doraemon plans to head down to the shop early after decorating the room, but when he reaches there the queue is already long. Doraemon ends up missing the first three rounds to help others in need; and has to rejoin the queue every time. With the sale of melon bread down to the last round, can Doraemon successfully buy the melon bread?