Shousetsu Tenki no Ko

Longing to escape his island home, a boy named Hodaka runs away during his first summer of high school to find a new life in Tokyo. As rain falls for days on end and Hodaka struggles to adjust, he meets a girl named Hina who holds a mysterious power: With a single prayer, she can part the clouds and bring back the sun. But her power comes at a price, and as the weather spirals further and further out of control, they must choose what future they truly want for themselves.

(Source: Yen Press)