Height 156 cm (5' 2") Nationality Japanese Affiliation Hakuryo Hiiragi (Class 3-B) Takeru's bubbly and klutzy childhood friend. She has a tendency to be very possessive when it comes to Takeru. The two lived next door to each other almost her entire life, and she can't imagine what life without Takeru would be, cherishing the memories the two have over everything. She's always kept her feelings for him to herself, expecting that nothing will change and the two will be together forever. But when Meiya enters the fray, she becomes determined to be more than just a childhood friend. Perpetually positive and optimistic, she's a firm believer in team spirit, and despite any conflict in love, she treasures her friends and is willing to do anything for them. Muv-Luv Unlimited Spoilers:

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In Unlimited, "Kagami Sumika" does not exist in this world. Despite scouring the sources available on the base near where her home once was, there are no records of her existence.

Muv-Luv Alternative Spoilers:

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In Alternative, it's revealed that the brain Shirogane Takeru frequently saw was, in fact, the remains of his childhood friend, Kagami Sumika. As Alternative IV was never completed, she couldn’t be turned into the pilot of the Susano'o and humanity's strongest weapon in the war against the BETA, the 00 Unit. A humanoid supercomputer with unparalleled ESP capabilities, emulating the personality of Kagami Sumika, obsessed with killing all of the BETA that killed Takeru and her.