Blue Period is based on a Japanese manga series of the same name written and illustrated by Tsubasa Yamaguchi. This anime series is about a second-year high school boy, Yatora Yaguchi. Yatora Yaguchi is an extremely dedicated and hardworking boy, who always excels in school but often deals with emptiness and self-doubt.
One day he gets fascinated by a painting that was kept in the art room, painted by a girl who was in the art club. He was so attracted to that painting, that he was tempted to try his hands at art. What followed is Yaguchi's descent into the beautiful world of art that fuels his passion for the same.
Spoilers for Blue Period!

Why Yatora Yaguchi choose studies over his passion?
The very first episode of the blue period shows us that Yaguchi is a very bright and famous kid. He is shown as a very hardworking boy who works very hard to achieve good grades so that he can do well in life. Yatora often ignores the fact that he is more into fine arts.
Surrounded by many judgmental people, he is very nervous to take any step toward his passion. Moreover, he belongs to a poverty-stricken background. This may be another reason for him to not follow his dreams and passion. Despite him scoring so well in exams, he struggles in being happy. In fact, he is usually quite miserable.

One day while mulling over his condition, he found himself mesmerized by a vibrant painting of Shibuya. He was so dumbfounded that he wasn't able to react to it at the moment. However, once he reached home, he picked up the paintbrush, hoping that his thoughts would be conveyed on the canvas.
Yatora was surrounded by talented peers. However, his lack of understanding of the importance of fine arts and the desire for his parents' approval put him in an adverse condition. He was unable to find happiness in what he was doing. On top of it, he was too conflicted and scared to take a step toward finding his passion.
What encouraged Yatora to paint?

It is shown in the very first episode of the Blue period that Yatora was shocked to the core after seeing a painting in the art club. He got into an argument with one of the members of the art club regarding the viability of becoming an artist.
He was approached by the Art club teacher herself, who challenged his notion of art. With all this going on in his mind that day, he went out with his friends and wasn’t able to convey his feelings even to them. The very next day he went into the art club and started painting Shibuya’s painting. He started imagining her scenery painting in different shades of blue.
Afterward, his painting was displayed on the board and was recognized by a lot of people. His friends recognized Shibuya’s painting. This is the very first-time Yatora was praised and recognized for who he really is and how he perceives things. This one art class helped Yatora to acknowledge himself better, his emotions, and also his perspective on life.

How did fine arts help Yatora in being a better son?
In episode 2 of Blue Period that Yatora is shown to be very punctual and sincere about his work. He finishes many assignments and even works over the summer break. He is doing everything he can do to be better at what he is doing. He wanted to pursue fine arts, but the major obstacle in his path was his mother and her opinion on education.
He wanted to convince his mother to go to a Fine Arts University. So he decided to impress her by drawing a portrait of her. Yatora started observing her mother for the same, and this led to many changes within him.
He started to observe her when she was doing the dishes, especially her hands- they were covered in bandages and cuts from doing dishes. Moreover, Yatora noticed her arm had become muscular due to carrying heavy groceries.
Here, Yatora felt terrible for not helping out his mother and also not noticing all this in the first place. So his passion really did help him a lot in becoming a better human and living a harmonious life.

Thanks for reading!