This anime is about how Rikka the girl with blue hair uses her imagination even though she's in high school. There's a sad background of why she is like that. the background of her story was because her dad died and she couldn't really have a good childhood. The boy in the picture is Togashi he tried helping her get out of it but it doesn't work out without her imagination she's different without it . so they let her stay like that in the end and they both got together. They also let her stay like that because she was happier in the world of her imagination .