He has long hair which is usually styled as a bun behind his head and dark brown eyes matching his hair as well as his eyebrows. He also appears to be growing a short scruff on his chin, his overall appearance makes him look way beyond his age yet slightly unapproachable.
In Season 2, he is shown no longer wearing his hair in a bun but swept backward with a sports hairband, which had been suggested to him by Kiyoko. In the Spring High Nationals arc, Asahi is shown wearing his hair back in a bun again.
In contrast to his appearance, he is rather quiet and gentle and has 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 "Glass Heart", taking everything that is said about him to heart, and becoming 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.
Asahi is the most powerful attacker in Karasuno. He is known for a strong spike that can blast past most defenders. As such, he is often trusted with the responsibility to score when faced with multiple blockers. His best spike is when he's given a high toss that is slightly away from the net. As his captain, Daichi, has said, "If you want to stop our ace, you'll have to bring an iron wall!".
Height and reach, as of mid-November:
- Fingertip Height: 242 cm
- Jumping Reach: 333 cm (spike) / 310 cm (block)
- Back Row Attack: After their battle against Nekoma, Asahi learned how to do a back row attack. He is usually seen using this attack in conjunction with Hinata acting as a decoy. With Hinata luring in the blockers, Asahi would take advantage of the opening to score. Eventually, he learned to perform this attack while syncing with Nishinoya's libero toss.
- Jump Serve: Asahi learned to perform a jump serve during the Summer Training Camp Arc. His jump serve has been noted by some to have a good course. Over time, his power and control have improved to which he can serve to difficult spots near the boundary lines.
- Delayed Spike: The delayed spike is one in which Asahi extends the time he stays in midair to throw off the blockers' timing. He would only spike when the blockers have started falling downward. The end result is a powerful wipe that sends the ball ricocheting off the blockers. He has successfully used this attack in pinch moments against teams like Date Tech, Tsubakihara, and Inarizaki. Sugawara eventually dubbed this attack as "Block Crusher".
- Favorite Food: Tonkotsu ramen
- Current Concern: When he tells people he's a student, nobody believes him; 1st years are afraid of him; girls in his class say things like "Even though he looks the way he does, he's kinda weak" and then get themselves disappointed; also his future plans; the captain being scary... (cut for length)
- Asahi wears white gym shoes with black accents.
- There are many rumors going around about Asahi mainly due to his physical appearance, including he is the leader of a gang, he deals illegal substances such as drugs, and he's been in high school for five years.
- His jersey number (3) is symbolic, considering how his specialty is spiking (and how spiking is usually the third contact) He, along with Daichi and Sugawara, form a set.
- Asahi and Yū Nishinoya are foils. Their birthdays are inverse (01/01 and 10/10), as are their heights and personalities (and even their name kanji contrast each other - respectively 'east' and 'west', 'peak' and 'valley', 'morning sun' and 'evening'). They are also the two best known, talented, and accomplished members of the team, other than Kageyama.
- His star sign is Capricorn.
- He went to Seukoudai Middle school.
- In the English dubbing of the anime, he is one of the few characters referred to by his first name instead of his last name.
- When asked about Asahi's name origin, Furudate said, “Because I finished the story and scene first - which doesn’t happen often - I made his name contrast to Nishinoya’s name: the morning sun which rises from the eastern peak!”
- In the Christmas Haikyuu!! Drama CD, Asahi mentions that 'Don't Give up, Kamchatka' is his Bible. It's a collection of photos and poems of people living in the harsh wilderness.
- In Haikyuu's first popularity poll, Asahi placed 7th with 3,418 votes. In the second, he dropped to 13th with 4,003 votes.
- Asahi (旭) - Morning Sun
- Azumane (東峰) - East Peak