I’m sorry it’s taken me longer than I said to look into this >.< I ended up with a migraine for most of the weekend, so I didn’t actually make it onto the laptop to look at anything. I’m feeling better now though, so I’ve just had a poke through the files! :3
I’m so glad you like Bitter/Sweet too ^-^ Blythe will always have an extra special place in my heart with that game being more personal than most of what I’ve made x3 If you happen to like the voice of the Blue Blythe, the same VA plays a main character in The Graveyard Shift too (the protagonist if you pick Shearsmith to be male!) :D
Anyways, regarding that last CG, if it was number 34, I looked at the code, and it says that the unlock condition is related to the support video call with Reiko the werewolf! The call with Reiko yields 3 different CGs depending on your choices with her :3
The choice that unlocks that last CG is if you simply listen to Reiko during the call, rather than attempting to provide any sort of advice. Helpful/Harmful advice unlocks the other 2 chibi CGs related to Reiko. Just listening unlocks Reiko’s special CG.
Hopefully, that helps :3