Kantai Collection character personifying the second of the 67 Tei-class (or D-class) coastal defense ships (kaibōkan), all of which were never formally named. She refers to herself through a goroawase nickname, Yotsu (よつ), sometimes spelled Yottsu (よっつ).
Her class was designated with even numbers while the C or Hei class (which numbered 53) were dubbed with odd numbers. Both classes were built as simplified versions of the Uruku-class due to Japan's deteriorating war situation; they also had similar designs. The Tei-class was given turbine engines due to the lack of diesel engines that were given to the Hei-class.
Yotsu has long brown hair that is tied into low twintails but with hair rings at the ends and brown eyes. She wears a white sailor hat, a white sailor dress with a blue sailor collar, blue accents, and a yellow bow, white socks, and a pair of uwabaki. Pinned to her left chest is a searchlight. Her machinery basically consists of a miniature version of her namesake ship slung to her left like a bag, an adapted turret, and several depth charges, one around each thigh and several in a canister near her person.
Despite being known only by a number, the historical escort ship made some contributions to Japan's war effort, having sunk two American submarines, USS Scamp on November 11, 1944 and USS Swordfish on January 4, 1945, although evidence for the latter is unclear. She was sunk by Royal Navy aircraft at Toba on July 28, 1945 and later salvaged and scrapped on June 30, 1948.