Sena is Akagi Kouhei’s little sister. While at first she pretends otherwise, Sena is a fujoshi, or “rotten woman” (a woman who loves yaoi). She often fantasizes about it; the idea of her brother and Kyousuke having a homosexual relationship is particularly pleasing to her. While she denies it, she is a brocon and has feelings for her brother. It is also shown that her brother cares deeply for her and, as Kyousuke says, is “a total siscon.”
Finally ending Kuroneko’s inability to make friends at high school, Sena becomes friends with her. The nature of their relationship is unknown, but Kyousuke is glad that Kuroneko finally was able to befriend someone.
Although despite of this she ended going out with her clubmate - Kaede Makabe.