One of the main themes is the battle of wits in love. Kaguya and Miyuki are both too proud to confess their love directly, so they engage in elaborate mind games. Another theme is the exploration of high - school relationships, including friendship and rivalry within the student council.
Kaguya is really interesting. Her internal struggle between her pride and her growing feelings for Miyuki makes her a complex character. Also, Miyuki is quite engaging with his intelligence and his own pride that gets in the way of expressing his love.