its been awhile ago, so my memories are quite dusty. I'm looking for a novel, wherein the MC is female, her sister married some high standing commander or whatnot, her parent being greedy they set up a condition, that if the guy married their daughter they have to take her too. So yeah buy one take one. She was then neglected as the guy don't give a shit about her, she snuck out and pretended to be a guy to join some knights academy thingy....more details I forgot.. Edit: After going through pages of novel titles, I finally found it!! Banzai!!