She is also the key to the "True World".
Sumire is a young high school girl with a kind heart. She loves all her friends dearly, and becomes upset when they are troubled or in danger. She joins the Venus Vanguard in order to help Lucia fight Viruses, depite being completely terrified of them. Through the series she bonds with the members of the Vanguard, particularly Lucia. Every time she faces a hardship and finds herself too weak, she vows to get stronger.
Her personality in Berserker form however is drastically different from her normal persona, at least until she learns to control it. While in Berserker form, Sumire feels no pain, and most likely few or no emotions, rendering her fearless in battle. She is shown to be violent in Berserker form as well, and hostile to friend and foe alike when out of control.
A young teenage high school girl with a petite figure and a height of about 5 feet and 1 inch. Sumire has short red hair that stops just above her shoulders which becomes slightly more flaired when in "berserker mode". She has emerald green eyes which change to red and gain pointed cross like pupil when in berserker mode similiar to those of viruses. It should be noted that when in her berserker mode Sumire speaks in a demented like voice. According to Sumire lucia gives of a faint smell of roses which is actually a part of their scant intertwined past.