Akane appears to be madly in love with him as shown in "Chapter 1" of the Manga and "Episode 1" of the Anime. She is a very yanderistic character which is shown when other woman tries to be near or have a relationship with Seiji. She can even kill them just for the sake of making him hers. In "Episode 5" she even goes as far as to even try to kill herself when she thought that Seiji was dead. Akane actually had met Seiji before the series had started. When Seiji was blinded by his pet cat, Akane helped Seiji with both the cat and as his guide. After aiding him, Seiji told Akane that she was very kind. Despite being told that by many people, Akane felt stronger toward Seiji because he could not see her beauty and truly believed she was kind by then. Since then, Akane fell in love with Seiji.
Guri and Akane are on bad terms since they are love rivals to Aino Seiji. Since the start of the story, Guri was not suppose to be with Seiji but after an unlikely event, it seems that Guri is attached to Seiji making Akane hate her for being by his side because Akane wants Seiji to herself. Akane even ried to kill her many times as well though out the story.
Yuzu is Akane's younger sister and only sees her as nothing more than her sister even though she was confessed to Yuzu a couple of times. Akane never gets into a fight with Yuzu because Yuzu only has eyes for Akane and not Seiji.
Being the cousin of Akane, she sees her as a threat as well after Shikimi tried to do something to Seiji. Akane always tries to protect Seiji from her grasp.