Konosuba: God's Blessing on This Wonderful World!, Vol. 10 (light novel): Gamble Scramble!

Luck be a lady tonight!Seeking financial support in the fight against the Demon King's army, Princess Iris visits the neighboring nation of Elroad to meet the prince: her husband-to-be. But Kazuma won't hand over his little sister to just anyone! Scratch that. He won't hand her over, period! Posing as her escort, he tags along in an attempt to derail yet another wedding (and rake in the dough). But no sooner than they arrive in Elroad are they informed that the engagement is off, and there won't be any financial support at all! And so it falls to Kazuma to use his wit and insanely good Luck to milk the Casino Kingdom for all it's worth!