She is first introduced in Episode 3. She is very much like a mother, like getting Aichi ready for school in the morning, and making sure he gets home at a reasonable time. She also has a tendency to overreact.
She attends Miyaji Academy, a school for rich girls.
In her first Vanguard fight in episode 15, Misaki lets Emi use her Oracle Think Tank deck. Since then, she has used Oracle Think Tank in her cardfights.
In episode 51 viewers are shown Emi building a new deck, which is centered the Bermuda △ clan. From the VG-EB02 Extra Booster: Diva Festival. She continues to use this deck (which she has called both cute and strong) quite effectively in episode 52.