Shun is bizarre and unpredictable, doing what he pleases without much thought or restraint. He tends to have a meaningful smile on him, and behaves or speaks mysteriously, but his close friends would be able to tell that they don't actually hold any deep meaning. He is also playful and fun-loving. While he dislikes and is weak against obligation, and often pushes some of this tasks as Procellarum's leader to Kai, he can actually work very earnestly, although it is unknown what he thinks about during those moments. Because of his upbringing as the sole child of the once-powerful Shimotsuki family, he is a real-life "rich boy" or a "princeling", or someone who has had a rather pampered upbringing, he also comes off as somewhat spoiled, and is weak to manual labor. He is also very intelligent, and is one of the students vying for the top spot at the national mock exams, together with Mutsuki Hajime and Yayoi Haru. He is also a great speed-reader, and can memorize a book after just one reading.