Kakekko

It's time to “place your bets." Anytime there's free time at school, the girls get together for their “betting game” where they put their dignity on the line. Friendships are abandoned and it's eat or be eaten.
Sunoyama Suzune is a bright and flamboyant first-year student at Yatagami Girls' High School. Tojo Yukina is a quiet but strong-willed girl. Whenever the two have free time on their hands, the place instantly becomes a gambling hall! A cute and wholesome life of gambling!

(Source: Comic-Meteor, translated)