This fanart is from the anime Golden Time.
Introduction to anime:
Banri finds himself completely lost after the opening ceremony and tries to find his way to the freshman orientation. Along the way, he runs into another lost freshman from the same school, Mitsuo Yanagisawa, and they immediately hit it off. Somehow arriving at their intended goal just in time, there appears in front of them a beautiful girl holding a bouquet of roses, who congratulates Mitsuo on getting into the school then hits him across the face with them before tossing the bouquet into his lap and leaving. This stylish, well dressed, and obsessive woman is his childhood friend, Kōko Kaga. As children, they had promised to marry each other one day, something she has taken to heart this entire time. Mitsuo had gone out secretly and taken the examination for this private college in order to escape from her, but she used her connections to find out about it, took the law school entrance examination, and enrolled in the college herself in order to be with him.