Gave it a shot, although I'm not too sure about the last panel, don't really understand the joke here. Did Naka mistake Ooi's initial words to mean that Mamiya was an idol as well and just ended up learning how to make candy by misunderstanding?
EDIT: Forgot to read the artist's commentary first and it seems that is the joke.
Ooi-san...The Navy's Idol Mamiya.Why!?Make a wonderful pastry shop!I'll beat that optimistic nature of yours into shape!Her candy making skill bloomed.Naka-chan having exerted extraordinary effort in her special trainingBut Naka-chan is an idol!A little girl like you can't possibly match Mamiya-san.The things that I have taught you are already....
ah, never mind.
