Chochin are portable lanterns made of a bamboo frame covered with paper or silk. A candle is placed inside as the light source. They can be folded flat when not in use. They were widely used during the Edo period for night time travel. In present times they are rarely used for that purpose. They are often used at festivals or outside bars to attract customers.
There are many different designs for these and different designs serve different purposes here are a few (there are many more):
-Akachochin are red lanterns usually found outside of establishments that serve liqueur.
-Gifu chochin were first produced in present-day Gifu Prefecture in the mid-18th century. The term Gifu paper lanterns encompasses o-uchi andon (lamp stands), rotating andon, andon that can adopt various shapes, and decorative lanterns. This type is often seen at the O-bon festival and Noryosai (a Japanese dance festival), both held in summer. These were designated a traditional craft in 1995.
-Odawara Chochin - Japanese paper is applied to a spiral-shaped coil of finely split bamboo, and rings are fitted to the top and bottom of the Chochin so it can be collapsed and folded flat. It was believed to protect people against evil spirits. Some of the materials for this Chochin are sometimes obtained from a holy mountain (Saijoji Temple, Mt. Daiyu).
In the picture at the top of this post Ranma and company have chochin that in the original say official business while searching for the gang that was cutting pigtails. Chochin can be seen fairly often in the Ranma manga and they use them as flashlights though using them in this manner is now uncommon. edit: added picture from volume 30.