I've never heard of BTB care to explain I can't find anything from google searching it.Like:
# Why Zack is doing this?
# is it really some student bet or something?
# What Zack had on Brooks?
# Why the other teacher quit/fired?
# What is Daniella doing?
# Is Nate really that innocent?
And Finally will we ever get a good BTB ending.
Most btb manga, erotica is one shot and few pages only. I have found only one game with more than one btb ending "Building our Futature".