Most likely not. Usually, songs like 'Haru Haru' are inspired by imagination or general emotions rather than specific true stories. It's more about artistic expression and creating a certain mood or theme.
Haru does love Legosi in the manga. It's evident in the way she cares for him, shows concern, and their shared experiences strengthen their bond, making it clear that her emotions towards him are those of love.
One possible story could be that Haru and the reader are at a beach. Haru suddenly does a really cool surfing move and the reader can't help but blush at his skill and confidence. Haru notices the reader blushing and comes over, making the reader blush even more.
One common theme is friendship. Haru and the reader often start as strangers and develop a deep friendship through shared experiences. Another theme is adventure. They might go on quests or travels together, exploring new places and facing challenges. Growth is also a theme, as both characters usually grow and change as a result of their relationship with each other.
I'm not entirely sure specifically as there could be many 'ao haru' light novels. Generally, a light novel could be about various things like a coming - of - age story, a fantasy adventure, or a slice - of - life tale in a Japanese - inspired setting.
Sure, Legosi and Haru do get together in the manga. Their relationship develops over time, facing various challenges but ultimately finding their way to each other.