Uso kara Hajimaru Koi no Natsu: Squall

When middle schooler Kaoru Tachibana runs away from home in the pouring rain, the last person she expects to bump into is her homeroom teacher, Mirei Shimotsuki. When Mirei takes her in for a few days, Kaoru is surprised to learn that the same woman who's normally so put together is actually a disorganized, laid-back day drinker behind closed doors. On the other hand, she's the only one who accepts Kaoru, struggles and all, and it's captivating. But with Mirei keeping her distance emotionally, what will become of their unusual relationship...?

(Source: Yen Press)