Chapters without someone peeing themselves: 19
This is what the letter really said.
But if there is a spy of some sorts and it ends up being another nameless character that suddenly gets introduced... then I really think Matsumoto Kouji needs to start fleshing out the people in the resistance. Because other then the people in Akira's group, we only know Master (Ryonusuke), his deceased wife and daughters, and... Tanaka. Maybe I'm missing other people but that's everyone I can remember from the top of my head.