Kenzan Good/Success End is possible. I just got it today. The GUIDE IS WRONG when it comes to getting Kenzan's ending.
Options to pick for Kenzan Good/Success End (will differ from guide):
Sorry I'm busy > 'You didn't do the paper' > Decline > Call him out. > '[Excuse that is NOT Play it Off.]' > Whatever flavor you like > No > Agree with Hiroko > Blame Alex. > Tell him everything. > Tell him about Akira > Hide under bed > Say nothing > Keep him here > The death of the child > No > Keep running! > Sunnersville > Kenzan Good/Success End
There may be other variations, but following the above steps worked for me.