Hi everyone, I’m the developer.
I’ve found a small mistake in the current version (1.3.1): In the skill tree, the "Coming soon..." text for the "Pass the B tier exam" description is missing. This might make it look like B-Rank is ready, but please note that B-Rank is not yet available.
I have already fixed this, but since my page is currently under review (Quarantine), I don't want to change or upload any files right now to avoid making the review process take even longer.
I will update the game with the fix as soon as the page is back to normal. Sorry for the confusion and thank you for your support!