Tamasei-ya's ohagi are made fresh every time, with only three flavors: coarse bean paste, smooth bean paste, and soybean flour. No unnecessary ingredients are used in the ohagi, resulting in a simple flavor made only with glutinous rice, bean paste, soybean flour, and sugar. Their timeless, gentle flavor is popular with people of all ages.

Their signature items are the three types of ohagi: fragrant kinako, tsubuan with a strong red bean flavor, and smooth koshian. The balance of sweetness and saltiness of the ingredients is exquisite, resulting in a simple yet memorable flavor. The kinako flavor is best-by the same day, while the tsubuan and smooth bean paste are best-by the next day. The packing and quantity rules are clear, and the two-type packs are lined up vertically, creating a neat appearance that's also popular.

The charm of the old-fashioned face-to-face sales style is that customers can watch the artisans swiftly prepare the products through the glass door while waiting for their turn. There is no eat-in option, and the shop normally sells the products in boxes to take home. There are often lines forming before the shop opens, and the shop closes when it sells out, which has also helped boost its popularity.