Usukawa-manju is cha-manju (steamed yeast bun with filling) smaller than its normal size. As the name suggests, it has a characteristic of having thin ('usu') skin ('kawa' that is made from flour and wraps sweet paste).
It is made in 'Kashiwa-ya', a time-honored confectioner since 1852, and it is a standard souvenir that is sold even in the shinkansen of the Tohoku Shinkansen line. It is found as a souvenir in parking areas in Fukushima Prefecture. Although its part of 'an' (sweet paste usually made from red azuki beans) is larger than the part of the skin, it is not too heavy, rather plain. There are two kinds of manju, which are 'koshi-an' (smooth paste) and 'tsubu-an' (paste containing pieces of azuki beans skin).
Some chain stores of Kashiwa-ya give demonstrations of making Usukawa-manju and let visitors have experience of making it (there is a charge for the experience).
It is also known as Tetsuji HONNA's parents' home, who is the music adviser for the upgrading project of Vietnam National Symphony Orchestra.