Hibiki's best friend, who shares a dorm with her and is often concerned for her safety.
~!While she served as a ordinary girl for the majority of the series, she became a temporary Symphogear user wielding the relic Shénshòujìng in G. She later gained use of the Faust Robe of Shénshòujìng in Senki Zesshō Symphogear XV.!~
Miku is helpful and cheery, but constantly worries about Hibiki due to the danger she frequently finds herself in as a Symphogear user. She has a hidden possessive streak towards Hibiki, borne out of a desire not to see Hibiki get hurt; even so, Miku does all her best to support Hibiki and encourages her to fight for what she believes in and help others, even if it's born of selfish desire, and so Miku works hard to make sure that Hibiki has a warm place to come home to.
~!In AXZ, it is revealed that years before the series, Miku had difficulty considering other people's feelings in general. She only cared about getting ahead of others and winning, and saw others as her rivals, wishing not to "see them from behind", like in her track-and-field races. However, Miku made an exception for Hibiki, with her hiding her pain behind a smile and her constant reckless helping of others despite the bullying she was suffering at the time. This led to Miku quitting track field upon transferring to Lydian upon the realization that she wanted to walk side-by-side with Hibiki, and taking up learning the piano as a way of expressing the inner feelings that Miku finds so hard to communicate.!~
(Source: Symphogear Wiki, edited)