Yeah, I'm stumped too. Since I've tried a ton of combinations already, you would think I would stumble upon at least one of the other unlockable endings. I also hope they release a walkthrough with how to unlock all endings for each route. Otherwise we will never get to see the special content for each guy.
Hi everyone!
This is Skyevina speaking here! We'll definitely post up the walkthrough for all the routes, once we fix up the major bugs in Prank Masters. We also want to apologise for the delay of updates. I've been doing best my best to fix up the bugs as fast as I can, and it's a lot harder when I have three jobs. But I'll let you know when the updates are out! I'm about 60% done with Richard's bug.
Thank you for your patience and support!