page 1 , panel 1 : there is an apple because apple is the fruit of knowledge . Forbidden fruit is a name given to the fruit growing in the Garden of Eden which God commands mankind not to eat. In the biblical narrative, Adam and Eve eat the fruit from the tree of the knowledge of good and evil and are exiled from Eden : https://en.wikipedia.org/wiki/Forbidden_fruit
page 5 : some whisperings that the 2 girls can hear clearly from 5 meters away , yeah right .
page 7 : in french language , pierre = stone , rock , and pommier = apple tree .
page 9 : main girl : yo , give me back the dirty leaf that i gave you as a gift of friendship .
i guess the macaron only increases her body heat , her muscles 's strength , makes her voice more louder , but it doesnt make her brain more smarter , lol .