For this activity a significant amount of prep and some cash investment on the side of the ALT is required!
SEE ATTACHED PHOTO
Each pumpkin is made up of a B4 sized sheet of orange craft paper and 2 paper fasteners. I cut each sheet into 7 strips and punched holes through the ends. Then through one of the sides, a paper fastener is used to secure them all to one point. With the students, the top (brown piece) is added and secured to the other side of the strips...then one can begin rotating out the strips (I found approximately half of the bundle at first is easiest). Many of the students found this initial process difficult so I would suggest showing the HRT this beforehand so both ALT and HRT can assist the students. More or less of the orange strips can be used, but since I had to purchase the materials, I found 7 to be perfect as 7 strips, ~4cm wide produced a nice round effect and used materials perfectly for the class size across 2 packs of paper. If time and budget aren't an obstacle, 10-15 strips 2-3cm wide makes a nicer pumpkin. Especially if the school is able to supply the materials and has a large paper cutter, I would suggest this approach over mine. Cutting out 32 pumpkins and a surplus of body parts to suit took about 6 hours using a craft knife and sicissors. To save some cash, one can purchase the like nearly a metre long sheets and cut them in half to render 2x B4 sheets of craft paper.
As I mentioned previously, I paired this activity with a lesson covering body parts and had the students ask for the body parts they wanted to complete the pumpkin with. If everything moves along somewhat smoothly approximately 20 minutes is required for the activity.
P.S. I don't think paper fasterners are something that are common in Japan as every store I went to had no idea what I was looking for and only one HRT at my school knew of them because their grandmother uses them occasionally for scrapbooking. The paperfasterners purchased through art/scrapbooking supply are frightfully expensive, but if one digs through Amazon long enough and searches IN JAPANESE you can find boxes of 50 for around 600円 shipped. The fasteners at scrapbooking stores are normally painted/decorative and are ~1500円+ for 20. If the amazon search is conducted in English, only imported office supply fasteners come up and are nearly twice as expensive as the scrapbooking stores. I reccomend the 15mm-20mm long ones.