Tsubaki

August Tsubaki Walker is sent to Japan to live with her father after her grandmother dies leaving behind her mother, step-father and younger sister and brother, who she didn't like, and joined her father, step-mother and 4 siblings. She takes on the name Mokoto Tsubaki and goes to high school with her older siblings, older twin brothers Matsu and Mitsu and her older (by 9 months) sister Mari. She also has a younger brother named Yuki(5). She really doesn't really make any friends but there is a boy named Kotako Rei who takes an interest in her. Everybody sees Rei as an delinquent because his dad is the leader of the well-known gang in Tokyo but he has a secret that he wants no one to find out.
(Sorry about the names I wanted them to go along with the theme but the story will be in English)