Rokka Melt: Fiancé wa Yukiotoko

In the "chilly love triangle" story, a super-athletic high school girl is suddenly betrothed one day — to two ikemen (handsome) brothers who happen to be snowmen. The younger brother is tsundere (initially aloof and abrasive, but later kind-hearted), while the older brother is irresponsible. Note: Includes five extra chapters.