Yumeko's surname, Jabami, can be translated to have any number of meanings; as the first kanji can mean "snake/serpent" or "hard drinker" and the second kanji translates to "eat", "drink", or "to receive a blow". The likeliest translation of her surname is "snake eater". Her first name, Yumeko, translates to "dream child".
In the first volume of the manga, it was revealed that Yumeko lives alone and her parents have passed away. She also has an older sister that is currently being hospitalized.
In the spin-off manga "Kakegurui (Kari)", Midari Ikishima is revealed to love animals. In the same chapter she is also revealed to be 'super sweet' in a romantic relationship.
Meari Saotome's surname translates to "young girl". It's literal translation can mean "young female rice planter" as well.