Doreiku - Boku to 23-nin no Dorei - Vol. 9 Ch. 23.1 - Setagaya Tsubaki 1

[MangaDex]

 

[kanadarica]

Didn't Julia and Seiya play a game when Julia didn't wear her SCM?

 

[Ominous]

Another late response. Answer: Yeah, they did. That was the chapter where we found out the game can be played without a SCM and the results can be finalized as long as you put on the SCM at any point during the game.