Koishicha Ikenai Hanakaze-kun

Sis-con high school girl Haruhi has zero interest in love! She's too busy guarding her cute little sister Hinata from guys on their way to school every day. Until one day when she finds herself caught in a pinch on the packed train, where a super-handsome stranger comes to her rescue! Who is he…?

(Source: Futabasha, translated)