In contrast to his appearance, he is rather quiet and gentle and has his difficulties realizing that he is Karasuno’s ace as he initially doesn’t feel that way. He shows to be weak-willed at the beginning when he leaves the team before the first years come, feeling that he let down his entire team when they lost against Date Tech High even though they counted on him. After coming back to Karasuno, he realizes that his will to play volleyball is much stronger than he thought and with the help of his teammates, he acknowledges his position as Karasuno’s ace (even though he is still mocked sometimes by Daichi for not having any “ace-like presence”) and gains self-confidence.
Asahi is said to have a “Heart of Glass”, taking everything that is said about him to heart and reacting depressed because of it at times. While he still feels insecure about a lot of things and seems to be quite a scaredy-cat, he clearly states that he has no intention of letting anyone take his ace position away from him in later chapters, showing his development from the beginning.