Yuzu
Yuzu (Citrus junos, family: Rutaceae) is one of the citrus fruits favored for its fragrant juice. Among all the citrus trees in Japan, yuzu is one of the hardy species that can tolerate low temperatures. Nevertheless, one of its major production area is the Kochi prefecture which located south of Japan.
The scale is in millimeters. The diameter is about 6.6 cm. Click here for a cross-section image of the yuzu seeds.
Other Citrus fruits
Mikan or Tangerine
This citrus fruit is by far the most favored in Japan -- mikan in Japanese, for eating them in winter while staying in kotatsu (a low-profile table with heating apparatus). They used to be sold in carton boxes and were eaten all winter when nothing fresh were available -- nowadays are usually sold in small packages.
Buntan or Pomelo
Buntan, or pomelo is one of the largest citrus fruits in Japan and is sold in the market as a special "gift fruit" from Kochi prefecture. It is favored for its fragrant flavor, fresh taste and its remarkable size. Its thick white cushion that surrounds the juicy pieces of fruits functions as a packaging material. Indeed, the fruits are transported in carton boxes without any filling materials.
Sudachi
Sudachi is considered to be a delicacy for its delicate flavored juice for fish dishes much in the same way as the lime juice is added for its flavor.