Atena grew up pretty sheltered from boys, so she's got this extreme reaction to being around them—she literally gets nosebleeds if she touches one. When Koushi shows up at her dorm, she's initially against him staying there, but after hearing what he's been through, she agrees to let him. She finds herself wanting to get closer to him, but then he starts calling her "sister," which hits her differently than expected. She actually asks him to keep calling her that, and takes on this protective role, making sure the other girls in the dorm don't try anything inappropriate with him.
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