There are many activities like this one for this grammar point, but I thought I would add my own!
For this activity to practice adjectival infinitives, I first showed a little review powerpoint and went over the grammar with the students. The powerpoint also reviews the new word 'something' that my 2nd year JHS students had just learned. Super quick presentation to just remind the students of the grammar and present the rules for the game.
Now, for the game, I made 8 different bags and pasted them onto construction paper. I printed 4 sets of the 8 bags (because I have about 32 students per class, you can print however many you need) and for each set of 8 I pasted them onto the same color paper. I did this so I didn't have to make 32 different bags lol. I told the students when it was time for the game that they can only talk to people with their same color.
Now, for the game, I attached the worksheet I made with a sample script of what they should say to find out what is in their partner's bag. I checked the Japanese with my JTE so hopefully everything is fine there. My JTE also wanted me to have everything on one page, so the worksheet is A3 size. You can make it two sheets of paper or front and back on A4, also.
I gave instructions and my JTE and I did a demonstration of interviewing each other to figure out what was in the other person's bag. This was really important as my students didn't really understand the game until the demonstration. Then, I set them loose and they walked around, found other students of their same color bag and interviewed them. You can change what is in the bags to match any vocab, I just went with what I thought would be simple because the grammar is quite difficult for this lesson. The students caught on very quickly once they started doing it and had a lot of fun figuring out the owner of each bag in their color group. I didn't give prizes to the fastest students, but you can definitely do that to increase motivation even more.
My students really liked this activity, and I think it helped them with a pretty difficult to grasp grammar concept (with a difficult name too lol), so I hope you find this helpful!