Tokoroten (心太, ところてん) is a dish in Japanese cuisine made from agarophytes. Tokoroten has been eaten by the Japanese for over a thousand years.^[1] Tokoroten is thought to have been introduced to Japan from China during the Nara period.^[2] Tokoroten was traditionally made by boiling tengusa (Gelidium amansii) and then allowing the mixture to congeal into a jelly.^[1]

Tokoroten was a popular snack during the summertime in Edo (Tokyo) during the Edo period.^[2] It was originally made to be eaten immediately and was commonly sold around factories.^[3] In the 17th century, it was discovered that freezing tokoroten would result in a stable and dry product known as kanten (agar).^[3][1] While tokoroten can be made from kanten based on seaweeds such as tengusa (Gelidiaceae) and ogonori (Gracilaria), today commercially produced kanten is mostly made from ogonori.^[2]

Pressed through an extruding device, the jelly is shaped into noodles. Unlike gelatin desserts, tokoroten has a firmer texture.

Tokoroten was and can be eaten hot (in solution) or cold (as a gel).^[3] Flavorings and garnishes can vary from region to region. Today, it is the most common to eat tokoroten with a mixture of vinegar and soy sauce,^[4] and sometimes nori,^[5] hot pepper, or sesame. In Kansai region, tokoroten is eaten as a dessert with kuromitsu.^[6]