If your confession is getting garbled then the game you're in is directly pulling from the system-level character encoding, and you're already in possession of a trivially reproducible way to force the game into undefined behavior. You guys are already hot on the trail of a potential exploit to enable arbitrary code execution; now is not the time for a test of courage.
This is assuming that senpai's motives are in line with the protagonist, though. Hareta wants to find a way to bug out the game so he can flip the bit that says "No Touchy Misaki" from a 1 to a 0, but senpai might be angling to Rowhammer the host machine and destroy their whole fucking universe.