Sakurai (櫻井螢 Sakurai Kei) was a descendant of a bloodline that allied the Obsidian Round Table during World War II. She joined the Table to fill the spot left by Beatrice Waltrud von Kircheisen, who had passed away 11 years prior. Her age had exactly matched her appearance as she was the youngest to join the LDO. She would later approach Ren to teach additional knowledge on fighting and had since then trained him to become an able fighter.