Hatsumei Princess

Shizuka, a genius inventor ( known as walking national treasure ) fell in love with Hajime, the Prime minister’s son when she was awarded at the Prime Minister’s house. Shizuka still pursuits and tries to invent something to make Hajime fall in love with her. But then when she invented a love potion she accidentally drank it and fell in love with some other guy….of course this made Hajime mad because the reason why Shizuka’s experiment is not working at Hajime is because…He’s already in-love with her.
From Manga Abyss:
Super genius inventor Shizuka, a.k.a. the walking National Treasure, fell in love at first sight with Hajime-kun when she was 10 years old. She hasn’t stopped pursuing him for 6 years! Every day, she worked hard to invent something that will get Hajime-kun to fall in love with her. Will she ever be able to win Hajime-kun’s heart?