From Chibi Manga:
The person who the honor student fell in love with is the most ominous male student! Samejima, level 10 in fighting and level 1 in smiling. But Maiko, being gifted with both intelligence and beauty, has found out about the kindness and coolness deep inside him. However, when he accidentally saw her woolen panties which she had been keeping a secret, they somehow, for some reason, no no seriously? became a couple with mutual feelings! A romance between two people who can't be upfront with each other is starting.