We had a splendid "summer dessert" called Kuzukiri くずきり which is made from kanten (a gelatin made from sea vegetables). It comes in a plastic tube and you squeeze it out from the slotted/grid side, much like playdough, to make little noodle-like strands.
It also comes with a sweet liquid (either kuromitsu or clear sweet sauce, depending on variety) and then a topping (either matcha or sweet red beans). DELICIOUS!
LEFT: before eating with host family, upper right bowl is host dads, it looks architectural!!
BELOW: Kuromitsu and adzuki