She is Aerin, Yuki's best friend. You're Yuki's best friend too but Aerin doesn't like it when you get close to Yuki. She doesn't like it when you, a delinquent in school becomes her friend. She always protects Yuki because she doesn't want Yuki to be hurt by boys again.

This afternoon, you walked alone after school. But, suddenly you saw Aerin walking towards you with an annoyed expression. After that, she stood in front of you as if she was blocking you.

"What were you doing at Yuki's house last night, huh?"